### Consecutive Numbers

An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.

### Calendar Capers

Choose any three by three square of dates on a calendar page...

### Days and Dates

Investigate how you can work out what day of the week your birthday will be on next year, and the year after...

# Bouncing Ball

##### Age 11 to 14 ShortChallenge Level

Working out the height after each time it hits the ground
First time: $\frac{3}{5}$ of 125 cm = 125$\div$5$\times$3 = 25$\times$3 = 75 cm.

Second time: $\frac{3}{5}$ of 75 cm= 75$\div$5$\times$3 = 15$\times$3 = 45 cm.

Third time: $\frac{3}{5}$ of 45 cm= 45$\div$5$\times$3 = 9$\times$3 = 27 cm.

Working out the height after each time it hits the ground using 3s and 5s
125 = 5$\times$5$\times$5
First time: $\frac{3}{5}$ of 125 is 3$\times$5$\times$5

Second time: $\frac{3}{5}$ of 3$\times$5$\times$5 is 3$\times$3$\times$5

Third time: $\frac{3}{5}$ of 3$\times$3$\times$5 is 3$\times$3$\times$3 = 27 cm.

Using powers
Each time the ball hits the ground, it bounces to $\frac{3}{5}$ of the height from which it fell. So after each bounce, its height is multiplied by $\frac{3}{5}$.

So after 3 bounces, its height will be multiplied by $\left(\frac{3}{5}\right)^3=\frac{27}{125}$.

So after 3 bounces, its height will be $125\times\frac{27}{125}=27$ cm.

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