2. There are 12 students in Phil's Maths group. The mean mark in a test is 76%. In Paul's group there are only eight students. Their mean mark is 84%. Find the overall mean for the 20 children.

1. Pete has seven Shetland ponies. They have a mean height of 116cm. Pete buys an eighth pony. The height of this pony is 128cm. Find the mean height of all eight ponies.

3. 50 students each did a mathematics test. The mean score for these 50 students was 8.4 There were 30 boys. The mean score for these 30 boys was 8,25 Work out the mean score for the girls.

4. 23 girls have a mean height of 153 cm. 17 boys have a mean height of 165 cm. Work out the mean height of all 40 children.​