Some pupils in two different classes take a test. There are 18 pupils in 7X1 and 26 pupils in 7Y1. The mean mark for the pupils in 7X1 is 23. The mean mark for pupils in 7Y1 is 17.
Calculate the mean mark for the two classes combined.
Give your answer correct to 1 decimal place.

Use the information given below, to compare the cost of operating two different vehicles for one month (4 weeks) you are considering two different cars. you drive to work, a 20 mile round trip, five days a week. gasoline costs you $1.50 per gallon car agets 28 miles per gallon, would have $300 a year in maintenance costs, and would cost you $1,500 per year to insure car b gets 19 miles per gallon, would have $500 a year in maintenance costs, and would cost you $1,000 per year to insure costs car a car b gas cost per month insurance cost per month maintenance cost per month $ total cost per month