Hong Kong
Stage 4 - Stage 5

# Applications of Recurrence Relations

## Interactive practice questions

A cake is taken out of a $156^\circ$156°C oven and left to cool in a room with a constant temperature of $26^\circ$26°C.

As soon as it is taken out, the temperature of the cake drops by $2.5^\circ$2.5°C each minute.

a

What is the temperature of the cake after $8$8 minutes?

b

Write a recurrence relation that gives the temperature $T_n$Tn of the cake after $n$n minutes in terms of $T_{n-1}$Tn1.

c

By how many degrees has the temperature of the cake dropped after half an hour?

d

Find the number of minutes it will take for the cake to reach room temperature.

Easy
5min

For a photo, the staff at a company have been arranged such that there are $9$9 people in the front row and each row has $2$2 more people than in the row in front of it.

Easy
4min

A basketball is dropped onto the ground from a height of $15$15 feet.

On each bounce, the ball reaches a maximum height of $55%$55% of its previous maximum height.

Easy
6min

Farhan has saved up $\$2540$$2540 to spend during his holiday to Lebanon. He plans to spend \310$$310 each week while he is there.

Let $t_n$tn be the amount of savings Farhan has left at the beginning of week $n$n.

Easy
3min