A hotel has 90 rooms. The table summarises information about the number of rooms occupied each day for a period of 200 days.

Number of rooms occupied 1-20 21-40 41-50 51-60 61-70 71-90

Frequency 10 32 62 50 28 18

i) Draw a cumulative frequency graph on graph paper to illustrate this information.

ii)Estimate the number of days when more than 30 rooms were occupied.

iii)On 75% of the days at most n rooms were occupied. Estimate the value of n