Q7 of 48 Page 125

The calculated mean of 50 observations was 80. It was later discovered that observation 19 was recorded by mistake as

91. What was the correct mean?

We know that



⇒ Sum of observations = Mean ×Total number of observations


Given mean of 50 observations = 80


⇒ Sum of 50 observations=80×50


⇒ Sum of 50 observations =4000


For correct mean, we will subtract 91 and add 19 to the sum.



More from this chapter

All 48 →
5

In a basket there are 10 tomatoes. The weight of each of these tomatoes in grams is as follows 60, 70, 90, 95, 50, 65, 70, 80, 85, 95.

Find the median of the weights of tomatoes.

 6

A hockey player has scored following number of goals in 9 matches.

5, 4, 0, 2, 2, 4, 4, 3, 3. Find the mean, median and mode of the data.

 8

Following 10 observations are arranged in ascending order as follows.

2, 3, 5, 9, x + 1, x + 3, 14, 16, 19, 20


If the median of the data is 11, find the value of x.

 9

The mean of 35 observations is 20, out of which mean of first 18 observations is 15and mean of last 18 observation is 25. Find the 18th observation.