Important for :

1

D

Let 1st number = x + 12, 2nd = xAverage = 19

(x + x + 12) | = 19 |

2 |

2x + 12 = 38

2x = 38 – 12

2x = 26

x = 13

1st = 25, 2nd = 13

Ratio = 25 + 2 : 13 + 2

= 27 : 15 = 9 : 5

Hence, option D is correct.

2

B

Let the number be x.
∴ |
1 | x – | 1 | x = 10 |

6 | 8 |

∴ |
8x – 6x | = 10 |

48 |

Hence, twice of the number is 480.

Hence, option B is correct.

3

C

Let the number = 4x, 5x4x – 4 : 5x – 4 = 3 : 4

(4x – 4) × 4 = (5x – 4) × 3

16x – 16 = 15x – 12

16x – 15x = 16 – 12

x = 4

Numbers = 16, 20

Now Ratio = (16 + 4) : (20 + 4)

= 20 : 24 = 5 : 6

Hence, option C is correct.

4

A

1st : 2nd = 5:62nd : 3rd = 15:16

1st : 2nd : 3rd = 5 × 15 : 6 × 15 : 6 × 16

= 75 : 90 : 96

= 25 : 30 : 32

Difference between the first and the thirst number = 700

32x - 25x = 700

7x = 700

x = 100

Number, 1st = 25 × 100 = 2500, 2nd = 30 × 100 = 3000, 32 × 100 = 3200

Average = | 2500 + 3000 + 3200 |

3 |

= | 8700 | = 2900 |

3 |

Hence, option A is correct.