[求助]2道DS题，大家帮帮忙呀``````````

A.Statement 1 ALONE is sufficient,2 is not.

B.Statement 2 ALONE is sufficient,1 is not.

C.Both 1 and 2 TOGEHTER are sufficient,but NEITHER  ALONE is sufficient.

D.EACH ALONE is sufficient.

E.1 and 2 TOGETHER are NOT sufficient.

1.Is the standard deviation of the set of measurements X1,X2,X3,X4,...X20 less than 3?(D)

(1)The variance for the set of measurements is 4.

(2)For each measurement,the difference between the mean and that measurement is 2.

第一点是什么意思，第二点我明白，因为每个数和平均数的差为2，所以偏差为2<3。

2.In City X last April,was the average (arithmetic mean) daily high temperature greater than the median daily high temperature?（B）

(1)In City X last April,the sum of the 30 daily high temperatures was 2,160°.

(2)In City X last April,60 percent of the daily high temperatures were less than the average daily high temperature.

这题我的理解是X市四月的平均日最高气温高于中间那天的日最高气温么？  第一点，30天的日最高气温达2160°，那就是平均每天最高温为72°（真不是一般的高）。第二点，30天中有18天的日最高温度低于平均日最高气温。  我觉得1、2两点都不能明确指出中间那天的日最高气温，无法进行比较，所以选了E