Room and board costs for selected schools are summarized in this distribution. Find the approximate cost of room and board corresponding to each of the following percentiles.
Costs (in dollars) Frequency
3000.5–4000.5 .....5
4000.5–5000.5 .....6
5000.5–6000.5 .....18
6000.5–7000.5 .....24
7000.5–8000.5 .....19
8000.5–9000.5 .......8
9000.5–10,000.5.....5
a. 30th percentile
b. 50th percentile
c. 75th percentile
d. 90th percentile