Suppose the ages of three persons are x, 2x, 3x years respectively

Hence, age of youngest person = x = 30 years.

A) 3 : 7 | B) 7 : 9 |

C) 4 : 5 | D) 1 : 3 |

Explanation:

Let their present ages be 13x and 17x.

Then, 13x-4/17x-4 = 11/15.

Solving this, we get x = 2.

Required ratio = 13x2 + 6/17x2 + 6 = 32/40 = 4/5.

A) 12.24 yrs | B) 13.25 yrs |

C) 16 yrs | D) 15.25 yrs |

Explanation:

Total ages of 80 boys = 15 x 80 = 1200 yrs.

Total age of 16 boys = 15 x 16 = 240 yrs

Total age of 25 boys = 14 x 25 = 350 yrs.

Average age of remaining boys = 1200 - (240+350) / 80 - (25+15) = 610/41 = 15.25 yrs.

A) E = 15 & Y = 3 | B) E = 14 & Y = 12 |

C) E = 40 & Y = 22 | D) E = 4 & Y = 2 |

Explanation:

Let the the age of the elder boy = E

Let the the age of the younger boy = Y

Given that Y = cube root of EY

=> = EY => E = .....(1)

By the condition of number replacement the age of the father is YE

The Mother's age = EY/2

But she is 3 years less than father => EY/2 + 3 = YE

2YE = EY + 6 ......(2)

Then now from the given options we can identify which satisfies the all the conditions.

Here Y =2 and E = 4 satisfies all the conditions.

A) 24 and 13 years | B) 48 and 24 years |

C) 35 and 11 years | D) 33 and 15 years |

Explanation:

Let the age of sushma be x and

the age of her son is y

Then five years before x-5=5(y-5) ...(1)

Five years hence x+5 = 3(y+5)-8 .....(2)

By soving (1) & (2), we get

5y - 15 = 3y + 7

y = 11 => x = 35

Therefore, the age of Sushma = 35 and her son = 11.

A) 2 : 5 | B) 8 : 15 |

C) 9 : 10 | D) 3 : 5 |

Explanation:

The ratio of X and Y ages at present is 4:5.

Then, the ratio 20 years ago will not be more than the ratio at present.

So, from the options 9:10 is not satifying => its ratio is 0.9 which is greater than presnt ratio of 0.8.