The number of quantities of the same kind is their sum divided by the number of quantities.
Average = (Sum of the Quantities / Number of the quantities)
The sum of the quantities = Average × the number of the quantities
- If a person covers a distance at x km/hr, and he again covers the same distance at a speed of y km/hr. Then his Average speed is-
- If a person covers three equal distances at a speed of x km/hr, y km/hr, and z km/hr. Then the average speed during the whole journey is-
- Average of first ‘n’ natural number is-
- Average of cubes of first ‘n’ natural numbers is-
- Average of squares first ‘n’ natural number is-
Q- 1. Find the average of first 10 multiples of 7.
Required Numbers = 7(1+2+3+4+5+6+7+8+9+10)
Here n = 10
Using Formula –
Average = (n + 1)/2
7(10 + 1)/2 = 77/2 = 38.5 (Ans.)
Q- 2. The distance between Point A and Point B is 778 km. A car covers the distance from A to B at 84 km/hr and returns to A with a uniform speed of 56 km/hr. Find the average speed of the car during the whole journey.
Let x = 84 km/hr, y = 56 km/hr
Using the Formula
= [(2 × 84 × 56)/(84 + 56)] = [(2 × 84 × 56) /140] = 67.2 km/hr