If three numbers are in the ratio of 3: 5: 7 and twice their sum is 60, find the square of the largest of the three numbers.

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  1. 100
  2. 225
  3. 196
  4. 625

Answer (Detailed Solution Below)

Option 3 : 196
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Given:

The ratio of three numbers is 3: 5: 7.

Twice their sum is 60.

Calculation:

Let the three numbers be 3x, 5x, and 7x.

The sum of the three numbers is 3x + 5x + 7x = 15x.

Twice their sum is given as 60:

2 × (15x) = 60

30x = 60

x = 60 / 30 = 2

The three numbers:

First number = 3x = 3 × 2 = 6

Second number = 5x = 5 × 2 = 10

Third number = 7x = 7 × 2 = 14

The largest of the three numbers is 14.

Square of the largest number = (14)2 = 14 × 14 = 196

∴ The square of the largest of the three numbers is 196.

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