How many trailing zeroes does 60! have?(A) 12(B) 9(C) 15(D) 14(E) 13 … [Read more...] about Number properties – Factorial

# GMAT Tough Math Questions

## Permutation of Digits & Divisibility

This is an interesting counting methods question that combines a very basic rule of test of divisibility of number by 3. Question How many six digit positive integers comprising only the digits 1 and 2 can be formed such that the number is divisible by 3? 3 20 22 38 360 Correct Answer Choice C. 22 such numbers can be formed. Video Explanation Explanatory … [Read more...] about Permutation of Digits & Divisibility

## Descriptive statistics – Standard Deviation

If m is the arithmetic mean (average) of 4 integers a, b, c, and d and s is the standard deviation of the 4 integers and s = , then is s > 0?(1) m > a(2) a + b + c + d = 0Solution:s will be zero only in two instances: (i) when all the elements in the set are the same, or (ii) the set contains only one element, which in this case is not possible. So, we need to check whether a, … [Read more...] about Descriptive statistics – Standard Deviation