Skip to main contentSkip to solution

The average of five consecutive numbers is a. If the next two numbers are also included, how will the average vary?

Solution

✅ Correct Option: 1
  1. Let's say first number is n. Then:
  • First 5 numbers: n, n+1, n+2, n+3, n+4
    • Next 2 numbers: n+5, n+6
  1. First 5 numbers average = a

= n+(n+1)+(n+2)+(n+3)+(n+4)5=a\frac{n + (n+1) + (n+2) + (n+3) + (n+4)}{5} = a

= 5n+105=a\frac{5n + 10}{5} = a

= n+2=an + 2 = a

  1. All 7 numbers average:

= n+(n+1)+(n+2)+(n+3)+(n+4)+(n+5)+(n+6)7\frac{n + (n+1) + (n+2) + (n+3) + (n+4) + (n+5) + (n+6)}{7}

= 7n+217\frac{7n + 21}{7}

= n+3n + 3

  1. Difference between averages:

= New average - Original average

= (n+3)−(n+2)(n + 3) - (n + 2)

= 11

Therefore, the average will increase by 1.

Keyboard Shortcuts

  • Left arrow: Previous question
  • Right arrow: Next question
  • S key: Jump to solution
  • Q key: Jump to question