Question

A person recorded the speed (in km/hr) of 10 motorists as 48, 52, 57, 55, 45, 39, 61, 49, 51 and 43. The average speed of the motorists is _____.

• A. 57 km/hr
• B. 50 km/hr
• C. 55 km/hr
• D. 54 km/hr

Answer 1

The correct option is B

50 km/hr

The speeds are 48, 52, 57, 55, 45, 39, 61, 49, 51 and 43 (in km/hr)

Sum of the speeds
$=48+52+57+55+45+39+61+49+51+43=500$

Number of motorists whose speeds were taken into account = 10
$\text{Average}$ = $\frac{\text{Sum of all the observations}}{\text{Total no. of observations}}$

$\text{Average Speed}=\frac{\text{Sum of the Speeds}}{\text{Number of motorists}}\therefore \text{Average Speed}=\frac{500}{10}=50km/hr$