 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.

Do the quiz now

1. The average of 5 quantities is 10 and the average of 3 of them is 9. What is the average of the remaining 2 ?

2. The average weight of 6 men decrease by 63 kg when one of them weighing 80 kg is replaced by a new man. Calculate the weight of the new man.

3. The average monthly income of P and Q is Rs. 5050. The average monthly income of Q and R is Rs. 6250 and the average monthly income of P and R is Rs. 5200. The monthly income of P is:

4. The average age of husband, wife and their child 3 years ago was 27 years and that of wife and the child 5 years ago was 20 years. The present age of the husband is:

5. The average weight of Ram, Sam and Sid is 45 kg. If the average weight of  Ram and Sam  be 40 kg and that of Sam and Sid be 43 kg, then the weight of Sam is:

6. A pupil’s marks were wrongly entered as 96 instead of 76. Due to that the average marks for the class got increased by half (1/2). The number of pupils in the class is:

7. The average of 5 quantities is 10 and the average of 3 of them is 9. What is the average of the remaining 2 ?

8. The average mark in a group of 25 students on a test is reduced by 2 when a new student replaces the topper who scored 95 marks. How many marks did
the new student have ?

9.

The average of 7 consecutive numbers is 33. The highest of these numbers is—

 Your points: Avg. points: 0