1. ## Grouped Data

Okay so i've been working through some problems with upper and lower quartiles and have so far been understanding it until i came up against this question....

The Manager of Sam and Ellea's Restaurant looked at the receipts for the last two days. The following table shows the range of values.
Amount of Receipt Frequency of Receipts Cumulative frequency
0-0.99 17 17
1.00-1.99 85 102
2.00-2.99 140 242
3.00-3.99 75 317
4.00-4.99 82 399
5.00-5.99 73 472
6.00-6.99 62 534
7.00-7.99 21 555
8.00-8.99 14 569
9.00-9.99 22 591
10.00-15.00 43 634

then they ask to find the upper quartile or Q3.....

this is what i figured out for the upper quartile though i believe i am wrong but here it goes;
14, 17, 21, 22, 43, 62, 73, 75 82, 85, 140

q3 = 62 + 73 / 2
= 67.5

however i don't believe this is the right way to find the q3 when using a chart... Thanks for any help in advance!

2. Originally Posted by lexx
Okay so i've been working through some problems with upper and lower quartiles and have so far been understanding it until i came up against this question....

The Manager of Sam and Ellea's Restaurant looked at the receipts for the last two days. The following table shows the range of values.
Amount of Receipt Frequency of Receipts Cumulative frequency
0-0.99 17 17
1.00-1.99 85 102
2.00-2.99 140 242
3.00-3.99 75 317
4.00-4.99 82 399
5.00-5.99 73 472
6.00-6.99 62 534
7.00-7.99 21 555
8.00-8.99 14 569
9.00-9.99 22 591
10.00-15.00 43 634

then they ask to find the upper quartile or Q3.....

this is what i figured out for the upper quartile though i believe i am wrong but here it goes;
14, 17, 21, 22, 43, 62, 73, 75 82, 85, 140

q3 = 62 + 73 / 2
= 67.5

however i don't believe this is the right way to find the q3 when using a chart... Thanks for any help in advance!
Just out of curiosity, where is 67.5 in the Amount of Receipt column ....?