Q14 of 14 Page 269

Mean of 100 items is 49. it was discovered that three items which should have been 60 70 80 were wrongly read as 40 20 50 respectively. The correct mean is -

Mean of 100 observations = 49



where x is sum remaining 97 observations


x + 110 = 1200


x = 1090 ..(i)


Adding 60, 70, 80 to the sum of remaining terms


= 1090 + 60 + 70 + 80


= 1300


Now finding means for 100 terms



So, the corrected mean is 13


More from this chapter

All 14 →
10

A class consists of 50 students out of which 30 are girls. The mean marks scored by girls is 73 and that of the boys is 71. Find the mean score of the whole class.

 11

The mean of 10 observations is 15.3. If two observations 6 and 9 are replaced by 8 and 14 respectively. Find the new mean.

 12

In a set of four integers the average of the two smallest integers is 102, the average of the three smallest integers is 103, the average of all four is 104. Which is the greatest of these integers?

 13

20 years ago when my parents got married their average age was 23 years now the average age of my family consisting of myself and my parents only is 35. My present age is?