The mean weight of 8 students is 45-5 kg. Two more students having weights 41-7 kg and 53-3 kg join the group. What is the new mean weight?
Solution:
The mean weight of 8 students = 45.5 kg
So, the total weight of 8 students = 45.5 x 8 = 364 kg
Weight of two more students are 41.7 kg and 53.3 kg
The total weight of 10 (8 + 2) students = 364 + 41.7 + 53.3
= 364 + 95
= 459 kg
Therefore, the new mean weight of all the 10 students = 459/10 = 45.9 kg
Mean of 9 observations was found to be 35. Later on, it was detected that an observation 81 was misread as 18. Find the correct mean of the observations.
Solution:
Mean of 9 observations = 35
So, the sum of all 9 observations = 35×9 = 315
Now, the difference due to misread = 81 – 18 = 63
Thus, the actual sum = 315 + 63 = 378
Therefore, the actual mean = 378/ 9 = 42.
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