### Bat Wings

Two students collected some data on the wingspan of bats, but each lost a measurement. Can you find the missing information?

### Kate's Date

When Kate ate a giant date, the average weight of the dates decreased. What was the weight of the date that Kate ate?

### Balancing the Books

How many visitors does a tourist attraction need next week in order to break even?

# Growing Families

##### Age 11 to 14 Short Challenge Level:

a) To find the average number of children per family, we need to know the total number of children, and divide this by the total number of families.

Number of children 1 2 3 4 5 total
Number of families 6 13 9 4 1 33
Total number of
children in families
this size
1$\times$6
= 6
2$\times$13
= 26
3$\times$9
= 27
4$\times$4
= 16
5$\times$1
= 5
80

80$\div$33 = 2.42

b) To find the average number of siblings, we need to know the total number of siblings of all of the children combined, and divide this by the total number of children.

Number of children 1 2 3 4 5 total
Number of families 6 13 9 4 1
Total number of
children in families
this size
1$\times$6
= 6
2$\times$13
= 26
3$\times$9
= 27
4$\times$4
= 16
5$\times$1
= 5
80
Number of siblings
each child in this
size family has
0 1 2 3 4
Total number of
siblings in families
this size
0$\times$6
= 0
1$\times$26
= 26
2$\times$27
= 54
3$\times$16
= 48
4$\times$5
= 20
148

148$\div$80 = 1.85

You can find more short problems, arranged by curriculum topic, in our short problems collection.