

Question

The table below shows the distribution of the waiting times for some customers in a certain petrol station.



Waiting time (in mins)
No of customers


1.5 - 1.9
3


2.0 - 2.4
10


2.5 - 2.9
18


3.0 - 3.4
10


3.5 - 3.9
7


4.0 - 4.4
2



(a) Write down the class boundaries of the distribution.
(b) Construct a cumulative frequency curve for the data;
(c) Using your graph, estimate: (i) the interquartile range of the distribution ; (ii) the proportion of customers who could have waited for more than 3 minutes.



The table below shows the distribution of the waiting times for some customers in a certain petrol station.



Waiting time (in mins)
No of customers


1.5 - 1.9
3


2.0 - 2.4
10


2.5 - 2.9
18


3.0 - 3.4
10


3.5 - 3.9
7


4.0 - 4.4
2


