7 At the theatre, the interval during a performance of King Lear lasts for 20 minutes and in that time 86 people need to use the toilet cubicles. On average, a person spends three minutes in the cubicle.

There are 10 cubicles available.

(a) Does the theatre have enough toilets to deal with the demand?

(b) If there are not enough cubicles, how long should the interval be to cope with demand?