Level 3
The average height of a group of 6 girls is 137 cm. When Kathy and Nicole joined the group, the average height increased by 4 cm. What is Kathy and Nicole's total height?
Level 3
The average mass of a group of girls was 37 kg. When Jamie, a girl, joined the group, the average mass of the group became 34 kg. If Jamie had a mass of 22 kg, how many girls were there in the group in the end?
Level 3
The ratio of the number of $2-notes to $10-notes in Dana's bag was 1 : 3. Dana exchanged 14 pieces of $10-notes for $2-notes. She then had an equal number of $2-notes and $10-notes. What was the total value of $2-notes and $10-notes in Dana's bag at first?
Level 3
The average height of some boys is 145 cm. When 3 girls, with a total height of 393 cm, are included, the average height if the children becomes 142 cm. How many children are there altogether?
