edited by
1,658 views

2 Answers

Best answer
9 votes
9 votes

$7200$ can be written as $2^{5} * 3^{2} * 5^{2}$

Therefore, there are $(5+1) * ( 2+1) * (2+1) = 54$ divisors including $1$, and $7200$.

Hence, the total divisors (excluding $1$ and $7200$) = $54-2 = 52$

Here's some justification to support the above method : 

Let $n\in\mathbb{N}$. Then by fundamental theorem of arithmetic we can write $n\in \mathbb{N}, n\neq 1$ by $n=p_1^{a_1}p_2^{a_2}\dots p_k^{a_k}$ where $p_1,p_2,\dots p_k$ are prime and $a_k\in\mathbb{N}$, $k=1,2,...,k$. Hence, number of divisors of $n$ =  $(a_1+1)(a_2+1)\cdots (a_k+1)$.

More on this here.

Answer ( C )

edited
0 votes
0 votes
7200=2^5 *3^2 * 5^2

total divisors=(5+1)*(2+1)*(2+1)=54

but 1 and 7200 excluding

so remaining divisors are 54-2=52

so ans is (C).
Answer:

Related questions

1.6k
views
2 answers
12 votes
Arjun asked Dec 18, 2018
1,582 views
What are the last two digits of $1! + 2! + \dots +100!$?$00$$13$$30$$33$$73$
1.4k
views
2 answers
3 votes
Arjun asked Dec 18, 2018
1,390 views
Let $m$ and $n$ be two positive integers. Which of the following is NOT always true?If $m$ and $n$ are co-prime, there exist integers $a$ and $b$ such that $am + bn=1$$m^...
1.2k
views
1 answers
1 votes
Arjun asked Dec 18, 2018
1,247 views
Consider the following toy model of traffic on a straight , single lane, highway. We think of cars as points, which move at the maximum speed $v$ that satisfies the follo...
995
views
1 answers
3 votes
Arjun asked Dec 18, 2018
995 views
Let $A$ and $B$ be two containers. Container $A$ contains $50$ litres of liquid $X$ and container $B$ contains $100$ litres of liquid $Y$. Liquids $X$ and $Y$ are solub...