Please to help slove the following maths. questions
1. A student is randomly selected from the group. Find the probability that
the score of the selected students is not greater than 65.
2. If the standard deviation of a, b, c, d and e is k, find the standard deviation
of 5a - 4, 5b - 4. 5c - 4, 5d - 4 and 5e -4
3. If the mean of the data set A: ( 7, 9, 15, 18, 20, m, n) is 14 and m and n are
both positive integers, which of the following must be true?
I. Range of the data set A<28
II. Median of the data set A = 15
III. If the datum "15" is removed from the data set, the mean will increase
4.The mean and the standard deviation of a group of 20 numbers are
10 and 2 respectively. When two more numbers, both are 10, are added,
the group of numbers has
a. mean = 10, standard deviation =2
b. mean = 10, standard deviation <2
c. mean > 10, standard deviation =2
d. mean < 10, standard deviation > 2