1) Emily has 24 unread emails in her mailbox, in which 6 of them are received today. Find the percentage increase in the unread emails today
2) After cutting a rope by 14.6 m, its length decreases by 18.25%. Find the length of the remaining part of the rope.
3) (a) Andy's expenditure of this month is 10% more than that of last month. If he spent $2400 last month, find his expendiyure of this month.
(b) If the expenditure of this month is 40% of his earnings, find his earnings.
4) Rebecca spent $12000 on buying the shares of a company at the beginning of February.After a month, the value of the shares increase by 12%.At the beginning of April, the value of the shares was 30% less than that at the beginning of March. What was the value of the shares at the beginning of April?
5) If hte numerator of 2/5 increases by 50% and its denominator decreases by 20%, find the new fraction.
5) The length and width of a rectangular lawn are 200 m and 150 m respectively. If the length and width decrease by 10% and 6% respectively,
(a) find the new area.
(b) find the percentage decrease in area.
6) The scores of team A and team B were the same at hte beginning of a competition. After a round, the score of team A increased by 80, and that of team B increased to 240.
(a) If the score of team A increased by 40%, find the scores of the two teams at the beginning.
(b) Find the percentage increase in the score of team B.
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Maths increase and decrease
2012-11-27 6:17 am
回答 (1)
2012-11-27 6:52 am
✔ 最佳答案
(1) Emily has 24 unread emails in her mailbox, in which 6 of them are received today. Find the percentage increase in the unread emails todayPercentage increase = increase/original x 100
increase=6
original= total unread - today [original no. emails = yesterday no. emails]
=6/(24-6) x 100
=50%
2) After cutting a rope by 14.6 m, its length decreases by 18.25%. Find the length of the remaining part of the rope.
18.25% = 14.6m
1% = 0.8
100%= 80m
3) (a) Andy's expenditure of this month is 10% more than that of last month. If he spent $2400 last month, find his expenditure of this month.
last month's expenditure = x = 2400
this month's expenditure = x * 110%
this month = 2400 * 1.1 = $2640
(b) If the expenditure of this month is 40% of his earnings, find his earnings.
let x = earnings
40% of x = $2640
x= 2640 / 40%
=2640/ 0.4
=$6600
4) Rebecca spent $12000 on buying the shares of a company at the beginning of February.After a month, the value of the shares increase by 12%.At the beginning of April, the value of the shares was 30% less than that at the beginning of March. What was the value of the shares at the beginning of April?
Feb = $12000
After a month = March = 12000 increase 12% = $12000 * 1.12 = $13440
April = 30% less than March = 70% of $13440 = $9408
5) If the numerator of 2/5 increases by 50% and its denominator decreases by 20%, find the new fraction.
numerator of 2/5 = 2
2 increase by 50% = 2 * 1.5 = 3
denominator of 2/5 = 5
5 decrease by 20% = 5 * 0.8 = 4
NEW FRACTION = 3/4
5) The length and width of a rectangular lawn are 200 m and 150 m respectively. If the length and width decrease by 10% and 6% respectively,
(a) find the new area.
200 decrease by 10% = 200 * 0.9 = 180m
150 decrease by 6% = 150 * 0.94 = 141m
area = 180 x 141
=25380m
(b) find the percentage decrease in area.
New area = 25380m
Old area = 200 x 150 = 30000m
Percentage decrease = decrease/original x 100
=(30000-25380) / 30000 x 100
=15.4%
2012-11-26 23:01:19 補充：
6) a) x= score at the beginning
80 = 40% of x
80 = 0.4x
x=200
b) Find the percentage increase in the score of team B
Percentage increase=increase/originalx100
=240/200*100
=120%
收錄日期: 2021-04-25 14:43:21
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