Urgent Questions(15) ^_^

用戶85377

2007-08-18 7:55 am

Show the steps very clearly. Tell me why also.
1. The mean of 10 data is calculated to be 48.7, with a datum 45 wrongly entered as 55. What is the correct mean of the 10 data?

2. If the mean, mode and median of two sets of data are the same, which of the following are true?
(i) All the data in both sets are the same.
(ii) Two sets of data contain same number of data.
(iii) Both frequency curves of the two sets of data are symmetric.

回答 (1)

用戶82723

2007-08-18 8:14 am

✔ 最佳答案

1. Let x be the sum of the remaining nine correct data. Then,
(x + 55) / 10 = 48.7
x = 432
So the correct mean of the 10 data = (432 + 45) / 10 = 47.7
2i) False
ii) False

eg (1,3,5,5,5,7,9) and (5,5,5) are two sets of data having the same mean, mode and median. But the total number of data are different and not all the data are the same.

iii) False.
The frequency curve is symmetric if and only if it is normal distribution (i.e. mean=mode=median) . However, the mean, median and mode of each set of data are not necessarily the same in this case.

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