# AVERAGE FOR UPSC CSAT PAPER II

1. Average:

Average = (Sum of observations / Number of observations)

2. Average Speed:

Suppose a man covers a certain distance at x kmph and an equal distance at y kmph.

Then, the average speed druing the whole journey is = [2xy/(x+y) ] kmph.

examples

1. In a class, the age of four students are 20 years, 22 years, 18 years, and 24 years, then what is the average age of the student of class ?

Solution :

By the above definition average age

= (20 + 22 + 18 + 24) /4 =84/4= 21 years

Therefore, average age of student = 21 years

2. If a person travels two equal distances at 10 km/hr and 30 km/hr .What is the average speed for the entire

journey ?

Average speed = [2 × 30 × 10/(30 + 10)]= [600/40] = 15 km/hr.

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