PSLE Linda spent $850 in November. This amount was a 15% decrease from what she spent in October. The amount she spent in December was a 20% increase from what she spent in November.
- What was the total amount that Linda spent from October to December?
- What was the percentage increase in the amount Linda spent in December compared to October?
|
Spending |
October |
100% |
|
Change |
- 15% |
|
November |
85% |
100 u |
Change |
|
+ 20 u |
December |
|
120 u |
(a)
Spending in October = 100%
Spending in November = 100% - 15% = 85%
85% = 850
1% = 850 ÷ 85 = 10
Spending in October
= 100%
= 100 x 10
= $1000
Spending in November = 100 u
Spending in December = 100 u + 20 u = 120 u
100 u = 850
1 u = 850 ÷ 100 = 8.5
Spending in December
= 120 u
= 120 x 8.5
= $1020
Total spending from October to December
= 1000 + 850 + 1020
= $2870
(b)
Increase in spending in December compared to October
= 1020 - 1000
= $20
Percentage increase
=
Increase in spendingSpending in October x 100%
=
201000 x 100%
= 2%
Answer(s): (a) $2870; (b) 2%