Q7 of 14 Page 269

Mean of 36 observation is 12. One observation 47 was misread as 74. Find the correct mean.

Mean of 36 observations = 12



where x is sum remaining 35 observations


x + 74 = 432


x = 358 ..(i)


Adding 47 to the sum of the remaining terms


= 358 + 47


= 405


Now finding means for 36 terms



So, the corrected mean is 11.25


More from this chapter

All 14 →
5

Mean of 50 observations was found to be 80.4 but later on it was discovered that 96 was misread as 69 at one place. Find correct mean.

 6

Is the mode always at the centre of the data?

 8

If the median of the series exceeds the mean by 3. Find the number by which mode exceeds its mean.

 9

The mean marks of boys and girls in an exam are 70 and 73. If mean marks of the whole class are 71, find the ratio of a number of girls to the number of boys.