Which of the following summation notations represents this series?
3 + 8 + 13 + + 23

First step in such tasks, is to find what is between each number.

8-3 = 5
13-8 = 5

13-23 = 10

Based on only the first 2, and the last one as a backup we can assume that it jumps with 5 each time, starting on 3. Hence the open spot should be:
18.

The correct answer is 18. :)

Step-by-step explanation:

Given that,

The total number of apples, T, is directly  proportional to the number of baskets,n,  of apples.

(a) Mathematically, it can be written as :

....(1)

Put T = 120 and n = 5

So,

(b) k is equal to 24. It means the constant of proportionality is 24.

(c) Put k = 24 and n = 8 in equation (1).

T = 24(8) = 192 apples

Hence, this is the required solution.