Answer:
Mean of resulting data = 7 times mean of original data=7a
Explanation:
Given that all values in a data set are multiplied by 7. to find the mean of the new set.
Let {x1,x2....xn} be the original data set.
The mean of this data set a=

Now multiply all values by 7
New data set
= {7x1, 7x2...7xn}
Sum of these = 7(x1+x2+..+xn) = 7 times sum of original data set
No of element = n for both the sets
Hence new mean = 7 * mean of original set.=7a
in other words, if the mean of the values in a data set is a. If each of the values in the data set were multiplied by 7, new mean would be 7a.