Maths_1－dkdqgav的部落格

標題:

Maths

發問:

Miss Wu saves 3/10 of her income each month.5/21of her expenditure is spent on cosmetics,1/6if it spent on transport and 2/5 of the remainder is spent on food. If she spent $400 on cosmetics and food altogether, how much does she save each month ?

最佳解答:

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7/10 of her income each month is on expenditure 5/21of her expenditure is spent on cosmetics. That is (7/10) x (5/21) = 1/6 of her income 1/6 of her expenditure is spent on transport. That is (7/10) x (1/6) = 7/60 of her income The remainder of the expenditure, excluding cosmetic and transport = 1 - 5/21 – 1/6 =25/42 Food is (2/5) x (25/42) = 5/21 of her expenditure Food is = (5/21) x (7/10) = 1/6 of her income Cosmetic and food are 1/6 + 1/6 = 1/3 of her income Her income $400 x 3 = $1200 She saves $1200 x 3/10 = $360 Miss Wu saves $360 each month Comment: How can she survive on $1200 per month in Hong Kong? She still manages to save $360! Please check the figures. The break-down: Income $1200 Expenditure $840 Saving $360 Cosmetic $200 (5/21 of expenditure) Transport $140 (1/6 of expenditure) Food = $200 ((5/21 of expenditure) Other expenditure = $300

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