Joe's expenditure last month was summarized as follows:
Item: rent Food Others
Expenditure($): 8000 3200 1500
In this month,the rent is increased by 5%and the expenditure on food is decreased by 12%.If Joe increases this month 's total expenditure By 10%,find the percentage change in the expenditure on 'others'.
Please list the steps THX
Maths questions
2007-09-30 5:38 am
回答 (2)
2007-09-30 5:43 am
✔ 最佳答案
Expenditude last month= 8000 + 3200 + 1500
= $12 700
So, expenditude this month
= 12 700 X (1 + 10%)
= $13 970
New expenditure on rent
= 8000 X (1 + 5%)
= $8400
New expenditure on food
= 3200 X (1 - 12%)
= $2816
Therefore, expenditure on others this month
= 13 970 - 8400 - 2816
= $2754
So, percentage change
= (New - old) / old X 100%
= (2754 - 1500) / 1500 X 100%
= 83.6%
參考: Myself~~~
2007-09-30 5:52 am
let x be the new expenditure on others,
8000x(1+5%) +3200x(1-12%) + x = (8000+3200+1500)x(1+10%)
8400 + 2816+ x = 13970
x =2754
percentage change in the expenditure on 'others:
(1- (2754 - 1500)/ 1500 )x100%
= (1 - 0.836 )x100%
=16.4
new expenditure on others decreases by 16.4%
8000x(1+5%) +3200x(1-12%) + x = (8000+3200+1500)x(1+10%)
8400 + 2816+ x = 13970
x =2754
percentage change in the expenditure on 'others:
(1- (2754 - 1500)/ 1500 )x100%
= (1 - 0.836 )x100%
=16.4
new expenditure on others decreases by 16.4%
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