Section B ( 40 marks )
7 . The following box-and-whisker diagram shows the number of hours spent shopping online of a group of 20 boys and 40 girls in a particular month .
3 7 8 x 12 ( a ) The inter-quartile range of the data is 4 . Find x .
( b ) Find the number of people in the group who spend at most 7 hours shopping online in that month .
The group of 20 boys spent a total of 120 hours of online shopping .
[ 2 ]
[ 2 ]
( c ) Find the mean number of hours that the boys spent shopping online in that month .
[ 2 ] It is given that the overall mean number of hours spent shopping online of all
60 people is 9 hours .
( d ) |
( i ) |
Find the total number of hours that all 60 people spent shopping |
|
|
online in that month . |
( ii ) Hence , find the mean number of hours that the girls spent shopping online in that month .
[ 5 ]
The standard deviation in the number of hours that the girls spent shopping online is 2 hours . It is also given that in the next month , the mean number of hours that the girls spent shopping online is increased by 1.5 hours .
( e ) |
( i ) |
Find the mean number of hours that the girls spent shopping |
|
|
online in the next month . |
( ii ) Find the variance in the number of hours that the girls spent shopping online in the next month .
[ 5 ]
© SE Production Limited 12 All Rights Reserved 2021