Page 90 - New Medley 5 Semester 2

4. David was asked to solve 60 questions. He solved 80% of the assignment
without his parents’ help. How many questions did he solve with his
parents’ help to complete the assignment?

5. Which amount is more—60% of `300 or 75% of `400?

6. In a stadium, 15% seats are reserved for the first class. If the number

of seats for the first class is 9000, find the number of total seats in
the stadium.

Average

The sum of two or more numbers divided by the counting of numbers

gives the result as an average. In other words, an average is a quotient
obtained from the division of the total sum by the number of quantities.

Consider the five numbers 4, 6, 9, 12 and 14.

Sum of these numbers = 4 + 6 + 9 + 12 + 14 = 45

Counting of these numbers = 5

Sumof numbers 45
 Average = = = 9
Countingof numbers 5

We can find the total of the numbers or observations by multiplying the

average with the number of observations.

Sumofall observations
Thus, Average =
Number of observations

and Sum of all observations = Average × Number of observations

Properties of an Average

Consider the average of following sets.

Sum = 4 + 6 + 8 = 18 kg

4 kg 6 kg
Number of values = 3

8 kg 18
Average = = 6 kg
3

88