There are 6 units in an exam course. Each unit is marked out of 100
To get grade A, the mean mark of all six units must be at least 80
Tom has taken five units. His mean mark is 78
To get grade A, how many marks must he get on the last unit?

It is saturday morning and jeremy has discovered he has a leak coming from the water heater in his attic. since plumbers charge extra to come out on the weekends, jeremy is planning to use buckets to catch the dripping water. he places a bucket under the drip and steps outside to walk the dog. in half an hour the bucket is 1/5 of the way full. what is the rate at which the water is leaking per hour?