shyind
If the sum of five consecutive positive integers is A, then the sum of the next five consecutive integers in terms of A is:
A. A+1
B. A+5
C. A+25
D. 2A
E. 5A
We can label each integer as follows:
First integer = x
Second integer = x + 1
Third integer = x + 2
Fourth integer = x + 3
Fifth integer = x + 4
Thus:
A = 5x + 10
A - 10 = 5x
(A - 10)/5 = x
A/5 - 2 = x
We see that the next 5 integers are x + 5, x + 6, x + 7, x + 8, and x + 9.
Since we have an evenly spaced set, sum = average x quantity, and since x = A/5 - 2, we have:
sum = (first term in the set + last term in the set)/2 x quantity
sum = [(A/5 - 2 + 5 + A/5 - 2 + 9)/2] x 5
sum = [(2A/5 + 10)/2] x 5
sum = (A/5 + 5) x 5
sum = A + 25
Alternate solution:
If we let the first integer be x, then the first five integers will be x, x + 1, x + 2, x + 3, and x + 4, and the next five integers will be x + 5, x + 6, x + 7, x + 8, and x + 9. We can see that each of the next five integers is 5 more than its counterpart in the first five integers. Thus, the sum of the next five integers is 5 x 5 = 25 more than the sum of the first five integers. So, if the sum of the first five integers is A, the sum of the next five integers is A + 25.
Answer: C