Cheenta Blog Since 2010

Mathematics is Beautiful
University Application
Guides
Books
ISI Entrance
Math Olympiad
বাংলা
All Posts
October 11, 2021
Infinite Series- ISI B.MATH 2006 | Problem - 1

Problem If $\sum_{n=1}^{\infty} \frac{1}{n^2} =\frac{{\pi}^2}{6}$ then $\sum_{n=1}^{\infty} \frac{1}{(2n-1)^2}$ is equal to (A) $\frac{{\pi}^2}{24}$ (B) $\frac{{\pi}^2}{8}$ (C) $\frac{{\pi}^2}{6}$ (D) $\frac{{\pi}^2}{3}$ Hint Try to write the summation as sum of square of reciprocal of odd numbers and even numbers and take the advantage of the infinite sum Solution $\sum_{n=1}^{\infty} \frac{1}{n^2} =\frac{{\pi}^2}{6}$ $\Rightarrow \sum_{n=1}^{\infty} \frac{1}{(2n)^2} + \sum_{n=1}^{\infty} \frac{1}{(2n-1)^2}= […]

Read More
October 9, 2021
A Probability Birthday problem along with Julia Programming

Probability theory is nothing but common sense reduced to calculation. Pierre-Simon Laplace Today we will be discussing a problem from the second chapter of A First Course in Probability(Eighth Edition) by Sheldon Ross. Let's see what the problem says: Describing the Problem The problem(prob-48) says: Given 20 people, what is the probability that among the […]

Read More
October 7, 2021
ISI B.Math objective 2006 problem -2 Number theory (Euler phi function)

PROBLEM Let $p$ be an odd prime.Then the number of positive integers less than $2p$ and relatively prime to $2p$ is: (A)$p-2$ (B) $\frac{p+1}{2} $(C) $p-1$(D)$p+1$ SOLUTION This is a number theoretic problem .We can solve this problem in 2 different methods. Let us see them both one by one Method -1 Let us look […]

Read More
October 4, 2021
Pi calculating from Mandelbrot Set using Julia

There should be no such thing as boring mathematics. Edsger W. Dijkstra In one of our previous post, we have discussed on Mandelbrot Set. That set is one of the most beautiful piece of art and mystery. At the end of that post, I have said that we can calculate the value of $\pi $ […]

Read More
September 30, 2021
Partition Numbers and a code to generate one in Python

Author: Kazi Abu Rousan The pure mathematician, like the musician, is a free creator of his world of ordered beauty. Bertrand Russell Today we will be discussing one of the most fascinating idea of number theory, which is very simple to understand but very complex to get into. Today we will see how to find […]

Read More
September 28, 2021
ISI B.STAT PAPPER 2018 |SUBJECTIVE

Problem Let $f$:$\mathbb{R} \rightarrow \mathbb{R}$ be a continous function such that for all$x \in \mathbb{R}$ and all $t\geq 0$ f(x)=f(ktx) where $k>1$ is a fixed constant Hint Case-1 choose any 2 arbitary nos $x,y$ using the functional relationship prove that $f(x)=f(y)$ Case-2 when $x,y$ are of opposite signs then show that $$f(x)=f(\frac{x}{2})=f(\frac{x}{4})\dots$$ use continuity to […]

Read More
September 28, 2021
I.S.I B.STAT 2018 | SUBJECTIVE -4

PROBLEM Let $f (0,\infty)\rightarrow \mathbb{R}$ be a continous function such that for all $x \in (0,\infty)$ $f(x)=f(3x)$ Define $g(x)= \int_{x}^{3x} \frac{f(t)}{t}dt$ for $x \in (0,\infty)$ is a constant function HINT Use leibniz rule for differentiation under integral sign SOLUTION using leibniz rule for differentiation under integral sign we get $g'(x)=f(3x)-f(x)$ $\Rightarrow g'(x)=0$ [ Because f(3x)=f(x)] […]

Read More
September 28, 2021
TESTING THE CONCEPT OF COPRIME NUMBERS | CMI 2015 PART B PROBLEM-3

PROBLEM Show that there are exactly $2$ numbers $a$ in the set $\{1,2,3\dots9400\}$ such that $a^2-a$ is divisible by $10000$ HINT Use Modular arithmetic and concepts of coprime numbers SOLUTION we know $10000=2^4*5^4$ In order for $10000$ to divide $a^2-a$ both $2^4$ and $5^4$ must divide $ a^2-a $ Write $a^2-a=a(a-1)$ Note that $a$ and […]

Read More
September 28, 2021
Best algorithm to calculate Pi - Part1

Author: Kazi Abu Rousan $\pi$ is not just a collection of random digits. $\pi$ is a journey; an experience; unless you try to see the natural poetry that exists in $\pi$, you will find it very difficult to learn. Today we will see a python code to find the value of $\pi $ up to […]

Read More
September 26, 2021
Monte Carlo Method to calculate Pi

Author: Kazi Abu Rousan Pi is not merely the ubiquitous factor in high school geometry problems; it is stitched across the whole tapestry of mathematics, not just geometry’s little corner of it. $\pi$ is truly one of the most fascinating things exist in mathematics. It's not just there in geometry, but it's also there in pendulum, […]

Read More
1 5 6 7 8 9 58
March 5, 2026
AMERICAN MATHEMATICS COMPETITION 10 A - 2017

Problem 1 What is the value of $(2(2(2(2(2(2+1)+1)+1)+1)+1)+1)$(A) 70(B) 97(C) 127(D) 159(E) 729 Answer: (C) 127 Problem 2 Pablo buys popsicles for his friends. The store sells single popsicles for $\$ 1$ each, 3popsicle boxes for $\$ 2$ each, and 5 -popsicle boxes for $\$ 3$. What is the greatest number of popsicles that Pablo […]

Read More
March 4, 2026
Indian National Mathematical Olympiad 2026

Problem 1. Let $x_1, x_2, x_3, \ldots$ be a sequence of positive integers defined as follows: $x_1=1$ and for each $n \geqslant 1$ we have $$x_{n+1}=x_n+\left\lfloor\sqrt{x_n}\right\rfloor$$ Determine all positive integers $m$ for which $x_n=m^2$ for some $n \geqslant 1$. (Here $\lfloor x\rfloor$ denotes the greatest integer less or equal to $x$ for every real number […]

Read More
March 4, 2026
American Mathematics Competition 8 - 2026

1 What is the value of the following expression? 1+2-3+4+5-6+7+8-9+10+11-12 A. 18 B. 21 C. 24 D. 27 E. 30 Answer - A 2 In the array shown below, three 3 s are surrounded by 2 s, which are in turn surrounded by a border of 1 s . What is the sum of the […]

Read More
February 13, 2026
American Mathematics Competition 10A - 2021

Problem 1What is the value of $\frac{(2112-2021)^{2}}{169}$ ?(A) 7(B) 21(C) 49(D) 64(E) 91 Answer: (C) 49 Problem 2Menkara has a $4 \times 6$ index card. If she shortens the length of one side of this card by 1 inch, the card would have area 18 square inches. What would the area of the card be […]

Read More
February 6, 2026
American Mathematics Competition 10A - 2020

Problem 1 What value of $\boldsymbol{x}$ satisfies $$x-\frac{3}{4}=\frac{5}{12}-\frac{1}{3} ?$$ (A) $-\frac{2}{3}$(B) $\frac{7}{36}$(C) $\frac{7}{12}$(D) $\frac{2}{3}$(E) $\frac{5}{6}$ Answer: (E) $\frac{5}{6}$ Problem 2 The numbers $3,5,7, a$ and $b$ have an average (arithmetic mean) of 15 . What is the average of $a$ and $b$ ?(A) 0(B) 15(C) 30(D) 45(E) 60 Answer: (C) 30 Problem 3 Assuming $a […]

Read More
February 6, 2026
American Mathematics Competition 10A - 2019

Problem 1 (A) 0(B) 1(C) 2(D) 3(E) 4 Answer: (C) 2 Problem 2What is the hundreds digit of $(20!-15!)$ ?(A) 0(B) 1(C) 2(D) 4(E) 5 Answer: (A) 0 Problem 3Ana and Bonita were born on the same date in different years, $n$ years apart. Last year Ana was 5 times as old as Bonita. This […]

Read More
February 4, 2026
American Mathematics Competition 10A - 2024

Problem 1What is the value of $9901 \cdot 101-99 \cdot 10101$ ?(A) 2(B) 20(C) 200(D) 202(E) 2020 Answer: (A) 2 Problem 2A model used to estimate the time it will take to hike to the top of the mountain on a trail is of the form $T=a L+b G$, where $a$ and $b$ are constants, […]

Read More
February 4, 2026
AMERICAN MATHEMATICS COMPETITION 8 - 2020
Read More
February 1, 2026
AMERICAN MATHEMATICS COMPETITION 10 A - 2021

Problem 1 What is the value of $\frac{(2112-2021)^{2}}{169}$ ?(A) 7(B) 21(C) 49(D) 64(E) 91 Answer: (C) 49 Problem 2 Menkara has a $4 \times 6$ index card. If she shortens the length of one side of this card by 1 inch, the card would have area 18 square inches. What would the area of the […]

Read More
January 25, 2026
American Mathematics Competition 10A - 2025

Problem 1 Andy and Betsy both live in Mathville. Andy leaves Mathville on his bicycle at $1: 30$, traveling due north at a steady 8 miles per hour. Betsy leaves on her bicycle from the same point at $2: 30$, traveling due east at a steady 12 miles per hour. At what time will they […]

Read More
1 5 6 7 8 9 105
April 23, 2026
AMC 10A 2002 Question Paper

Question 1 The ratio \(\frac{10^{2000}+10^{2002}}{10^{2001}+10^{2001}}\) is closest to which of the following numbers? (a) 0.1 (b) 0.2 (c) 1 (d) 5 (e) 10 Question 2 For the nonzero numbers \(a, b, c\), define \((a, b, c)=\frac{a}{b}+\frac{b}{c}+\frac{c}{a}\). Find \((2,12,9)\). (a) 4 (b) 5 (c) 6 (d) 7 (e) 8 Question 3 According to the standard convention […]

Read More
April 23, 2026
AMC 10A 2003 Question Paper

Question 1 What is the difference between the sum of the first 2003 even counting numbers and the sum of the first 2003 odd counting numbers? (a) 0 (b) 1 (c) 2 (d) 2003 (e) 4006 Question 2 Members of the Rockham Soccer League buy socks and T-shirts. Socks cost \($ 4\) per pair and […]

Read More
April 23, 2026
AMC 10A 2004 Question Paper

Question 1 You and five friends need to raise \($ 1500\) in donations for a charity, dividing the fundraising equally. How many dollars will each of you need to raise? (a) 250 (b) 300 (c) 1500 (d) 7500 (e) 9000 Question 2 For any three real numbers \(a, b\), and \(c\), with \(b \neq c\), […]

Read More
April 23, 2026
AMC 10A 2005 Question Paper

Question 1 While eating out, Mike and Joe each tipped their server 2 dollars. Mike tipped \(10 %\) of his bill and Joe tipped \(20 %\) of his bill. What was the difference, in dollars between their bills? (a) 2 (b) 4 (c) 5 (d) 10 (e) 20 Question 2 For each pair of real […]

Read More
April 23, 2026
AMC 10A 2006 Question Paper

Question 1 Sandwiches at Joe's Fast Food cost \($3\) each and sodas cost \($ 2\) each. How many dollars will it cost to purchase 5 sandwiches and 8 sodas? (a) 31 (b) 32 (c) 33 (d) 34 (e) 35 Question 2 Define \(x \otimes y=x^{3}-y\). What is \(h \otimes(h \otimes h)\) ? (a) \(-h\) (b) […]

Read More
April 22, 2026
AMC 10A 2014 Question Paper

Question 1 What is $10 \cdot\left(\frac{1}{2}+\frac{1}{5}+\frac{1}{10}\right)^{-1}$ ? (a) 3 (b) 8 (c) $\frac{25}{2}$ (d) $\frac{170}{3}$ (e) 170 Question 2 Roy's cat eats $\frac{1}{3}$ of a can of cat food every morning and $\frac{1}{4}$ of a can of cat food every evening. Before feeding his cat on Monday morning, Roy opened a box containing 6 cans […]

Read More
April 22, 2026
AMC 10A 2024 Question Paper

Question 1 What is the value of $9901 \cdot 101-99 \cdot 10101$ ? (a) 1 (b) 20 (c) 200 (d) 202 (e) 2020 Question 2 A model used to estimate the time it will take to hike to the top of the mountain on a trail is of the form $T=a L+b G$, where $a$ […]

Read More
April 22, 2026
AMC 10A 2022 Question Paper

Question 1 What is the value of $$ 3+\frac{1}{3+\frac{1}{3+\frac{1}{3}} ?} $$ (a) $\frac{31}{10}$ (b) $\frac{49}{15}$ (c) $\frac{33}{10}$ (d) $\frac{109}{33}$ (e) $\frac{15}{4}$ Question 2 Mike cycled 15 laps in 57 minutes. Assume he cycled at a constant speed throughout. Approximately how many laps did he complete in the first 27 minutes? (a) 5 (b) 7 (c) […]

Read More
April 22, 2026
AMC 10A 2021 Question Paper

Question 1 What is the value of $$ \left(2^{2}-2\right)-\left(3^{2}-3\right)+\left(4^{2}-4\right) ? $$ (a) 1 (b) 2 (c) 5 (d) 8 (e) 12 Question 2 Portia's high school has 3 times as many students as Lara's high school. The two high schools have a total of 2600 students. How many students does Portia's high school have? (a) […]

Read More
April 22, 2026
AMC 10A 2020 Question Paper

Question 1 What value of $\boldsymbol{x}$ satisfies $$ x-\frac{3}{4}=\frac{5}{12}-\frac{1}{3} ? $$ (a) $-\frac{2}{3}$ (b) $\frac{7}{36}$ (c) $\frac{7}{12}$ (d) $\frac{2}{3}$ (e) $\frac{5}{6}$ Question 2 The numbers $3,5,7, a$ and $b$ have an average (arithmetic mean) of 15 . What is the average of $a$ and $b$ ? (a) 0 (b) 15 (c) 30 (d) 45 (e) […]

Read More
1 5 6 7 8 9 221
© 2010 - 2025, Cheenta Academy. All rights reserved.
linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram