PSLE Linda spent $640 in October. This amount was a 20% decrease from what she spent in September. The amount she spent in November was a 50% increase from what she spent in October.
- What was the total amount that Linda spent from September to November?
- What was the percentage increase in the amount Linda spent in November compared to September?
|
Spending |
September |
100% |
|
Change |
- 20% |
|
October |
80% |
100 u |
Change |
|
+ 50 u |
November |
|
150 u |
(a)
Spending in September = 100%
Spending in October = 100% - 20% = 80%
80% = 640
1% = 640 ÷ 80 = 8
Spending in September
= 100%
= 100 x 8
= $800
Spending in October = 100 u
Spending in November = 100 u + 50 u = 150 u
100 u = 640
1 u = 640 ÷ 100 = 6.4
Spending in November
= 150 u
= 150 x 6.4
= $960
Total spending from September to November
= 800 + 640 + 960
= $2400
(b)
Increase in spending in November compared to September
= 960 - 800
= $160
Percentage increase
=
Increase in spendingSpending in September x 100%
=
160800 x 100%
= 20%
Answer(s): (a) $2400; (b) 20%