Question

If I start with 3 and count by 4's until I reach 99, I get 3, 7, 11, …, 99, where 3 is the first number, 7 is the second number, 11 is the third number, and so on. If 99 is the Nthnumber, what is the value of N?

Answer 1

Given variables:

a=3

d=4

Tn=99

N=?

Using the formula

Tn=a+(n-1)d

99=3+(n-1)4

96=4(n-1)

24=n-1

25=n

Therefore N=25