Q6 of 174 Page 571

If the arithmetic mean of 7, 9, 11, 13, x, 21 is 13, find the value of x.

Sum of numbers = 7 + 9 + 11 + 13 + x + 21 = 61 + x

Number of observation = 6

Arithmetic Mean =

= 13 =

= 61 + x = 13 × 6 = 78

= x = 78 – 61 = 17.

The daily minimum temperature recorded (in degree F) at a place during a week was as under:

Monday	Tuesday	Wednesday	Thursday	Friday	Saturday
35.5	30.8	27.3	32.1	23.8	29.9

Find the mean temperature.

The percentage of marks obtained by 12 students of a class in mathematics are

64, 36, 47, 23, 0, 19, 81, 93, 72, 35, 3, 1.

Find the mean percentage of marks.

The mean of 24 numbers is 35. If 3 is added to each number, what will be the new mean?

The mean of 20 numbers is 43. If 6 is subtracted from each of the numbers, what will be the new mean?