Question

The average of 7 numbers is 28. If the sum of the first two numbers is two-fifth of the sum of the last five numbers, then the average of the last five numbers is?  
1. 28 
2. 30 
3. 32
4. 26
5. 35

Answer 1

Correct Answer - Option 1 : 28 

Given:

Average of 7 numbers = 28

Sum of first two = 2/5 × sum of last five

Formula used:

Average = sum of observations/total number of observations

Calculation:

Sum of 7 numbers = 7 × 28 = 196

First two numbers : last five numbers = 2 ∶ 5

Total sum = 7 ratio

∴ Sum of last five numbers = 5/7 × 196 = 140

Average = 140/5 = 28 

∴ The average is 28