1.

Of three positive numbers, the ratio of first and second is 4 ∶ 7, that of second and third is 2 ∶ 3. The product of first and third is 4200. What is the sum of the three numbers?1). 2252). 2153). 2504). 235

Answer»

Let the three numbers be X, y and z.

Ratio of x and y = 4 ? 7

Ratio of y and z = 2 ? 3

Then, x ? y ? z = 8 ? 14 ?21

Let the three NUMBER be 8A, 14a and 21a.

The product of x and z = 4200

⇒ x × z = 4200

⇒ 8a × 21a = 4200

⇒ a2 = 25

⇒ a = 5

First number = x = 8a = 40

Second number = y = 14a = 70

Third number = z = 21a = 105

The SUM of three numbers = 40 + 70 + 105 = 215



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