Solutions

Question

If the sum of the consecutive integers from –42 to n inclusive is 372, what is the value of n?

 

Difficulty Level

Medium

Solution

Option D is the correct answer.

Option Analysis

Number of terms =42+1+n=(n+43)

To find the sum = Formula = (n/2)(a+l), where n is the number of terms and ‘a’ and ‘l’ is the first term and last term.

Sum=372=((n+43)∗(n−42))/2

744=(n+43)∗(n−42) n=50

OR

42 terms after zero and 42 terms below zero will total 0. So, our new question will be consecutive integers with first term 43 have sum 372, what is the last term: ((43+n)/2)∗(n−43+1)=372 (n+43)∗(n−42)=744 n=50