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74. In an alloy, the ratio of copper and zinc is 5 : 2. If 1.250 kg of zinc is mixed in 17 kg 500 gm of alloy, then the ratio of copper and zinc will be = ?
i.e 5x : 2x
Quantity of initial mixture = 17.5 kg
∴ 5x + 2x =
⇒ x =
Quantity of Copper in initial mixture
Quantity of Zinc in initial mixture
Now after adding 1.250 kg of zinc
= 5 + 1.250
= 6.250 kg
=
∴ New Ratio of copper : zinc
Solution:
The ratio of copper and zinc is 5 : 2i.e 5x : 2x
Quantity of initial mixture = 17.5 kg
∴ 5x + 2x =
⇒ x =
Quantity of Copper in initial mixture
Quantity of Zinc in initial mixture
Now after adding 1.250 kg of zinc
= 5 + 1.250
= 6.250 kg
=
∴ New Ratio of copper : zinc
75. The income of A, B and C are in the ratio 7 : 9 : 12 and their spending are in the ratio 8 : 9 : 15. If A saves th of his income then the savings of A, B and C are in the ratio of = ?
and expenditure of A, B and C are 8y, 9y and 15y respectively
∴ The ratio of savings of A, B and C
⇒ (7x - 8y) : (9x - 9y) : (12x - 15y)
⇒ (7 × 32 - 8 × 21) : (9 × 32 - 9 × 21) : (12 × 32 - 15 × 21)
⇒ (224 - 168) : (288 - 189) : (384 - 315)
⇒ 56 : 99 : 69
Solution:
Let income of A, B and C are 7x, 9x and 12x respectivelyand expenditure of A, B and C are 8y, 9y and 15y respectively
∴ The ratio of savings of A, B and C
⇒ (7x - 8y) : (9x - 9y) : (12x - 15y)
⇒ (7 × 32 - 8 × 21) : (9 × 32 - 9 × 21) : (12 × 32 - 15 × 21)
⇒ (224 - 168) : (288 - 189) : (384 - 315)
⇒ 56 : 99 : 69
76. What will be the simplest form of the ratio 3 hours : 1 day?
∴ Given ration = 3 : 24
= 1 : 8
Solution:
1 day = 24 hours.∴ Given ration = 3 : 24
= 1 : 8
77. In a proportion the product of 1st and 4th terms is 40 and that of 2nd and 3rd terms is 2.5x. Then the value of x is.
Solution:
Product of 1st and 4th terms (extremes) = product of 2nd and 3rd terms (means)
79. Two numbers are in the ratio 17 : 45, One - third of the smaller is less than of the bigger by 15. The smaller number is = ?
Solution:
80. 25% of A's income is equal to 35% of B's income. The ratio of the incomes of A and B is -
Solution: