Maths - Average

Average: The average of any set of quantities can be found by adding all the numbers together then dividing by the number of quantities in the set.i.e. average = total of quantities / number of quantities e.g. A darts player throws the following scores during a match:  80, 100, 62, 180, 21, 55
Her average score per throw = (80 + 100 + 62 + 180 + 21 + 55) ÷ 6 = 83
Arithmetic Mean Definition:      Arithmetic mean is commonly called as average.Mean or Average is defined as the sum of all the given elements divided by the total number of elements.
  Formula: Mean = sum of elements / number of elements
              = a1+a2+a3+.....+an/n
  Example: To find the mean of 3,5,7.
      Step 1: Find the sum of the numbers.           3+5+7 = 15
      Step 2: Calculate the total number.   there are 3 numbers.
      Step 3: Finding mean.           15/3 = 5
                                                Excersie

1. David obtained 76, 65, 82, 67 and 85 marks out of 100 each in respective subjects. His average marks are:

             a. 65 b. 69 c. 72 d. 76 e. none

2. The average of first five multiples of 3 is:

                a. 3 b. 9 c. 12 d. 15

3. The average of 2, 7, 6 & x is 5, and the average of 18, 1, 6, x & y is 10. what is the value of y?

               a. 5 b. 10 c. 20 d. 30

4. The average of first 50 natural numbers is:

               a. 12.25 b. 21.25 c. 25 d. 25.50

5. The average age of the boys in the class is 16 years and that of the girls is 15 years. The average age for the whole class is:

                 a. 15 b. 15.5 c. 16 d. cannt find

6. The average of 5 numbers is 27. If one number is excluded the average becomes 25. The excluded number is:

                  a. 25 b. 27 c. 30 d. 35

7. The average age of 35 students in a class is 16 years. The average age of 21 students is 14. The average age of remaining 14 students is:

                  a. 15 b. 17 c. 18 d. 19

8. The average of six numbers is 3.95. The average of first two is 3.4 and last two is 3.85. What is the average of remaining two:

                  a. 4.5 b. 4.6 c. 4.7 d. 4.8

9. The average of a cricket player of 10 innings was 32. How many runs must he make in his next innings so as to increase his average by 4 runs?

                  a. 2 b. 4 c. 70 d. 76

10. Of the four numbers whose average is 60, the first is one-fourth of the sum of the last three. The first number is:

                  a. 15 b. 45 c. 48 d. 60.25
Answer: 1e, 2b, 3c, 4d, 5d, 6d, 7d, 8b, 9d, 10c