A) 4:1 | B) 5:3 |

C) 16:1 | D) 1:16 |

Explanation:

Time taken by 8th tap = = 8 hours

and time taken by 12th tap = = hour

Ratio of time taken by 8th 8th tap and 12th tap = =16:1

Therefore, Ratio of efficiencies of 8th tap and 12th tap =1:16

A) 8.7 hrs | B) 5.2 hrs |

C) 5 hrs | D) 7.5 hrs |

Explanation:

Ratio of times taken by A and B = 160 : 100

A can do the work in 12 days

Let B can do the work in "D" days

=> 160:100 = 12 : D

=> D = 12 x 100/160 = 7.5 hrs

A) Total work | B) One-fourth work |

C) Half work | D) Two-third work |

Explanation:

A can do the work = 18 days

B can do the work = 18/2 = 9 days

(A + B)'s 1 day work = 1/18 + 1/9 = 1/6

=> In 3 days = 3x1/6 = 1/2 work is completed.

A) 13 days | B) 10 days |

C) 7 days | D) 16 days |

Explanation:

1 boy's 1 day work = 1/70

1 girl's 1 day work = 1/140

(5 boys + 10 girls)'s 1 day work

= (5/70 + 10/140) = (1/14 + 1/14) = 1/7

5 boys and 10 girls will complete the work in 7 days.

A) 9 days | B) 11 days |

C) 13 days | D) 15 days |

Explanation:

Ratio of times taken by A and B = 100 : 130 = 10 : 13.

Suppose B takes x days to do the work.

Then, 10 : 13 :: 23 : x => x = ( 23 x 13/10 ) => x = 299 /10.

A's 1 day's work = 1/23 ;

B's 1 day's work = 10/299 .

(A + B)'s 1 day's work = ( 1/23 + 10/299 ) = 23/299 = 113 .

Therefore, A and B together can complete the work in 13 days.

A) 10 days | B) 14 days |

C) 11 days | D) 9 days |

Explanation:

30 x 25 = 750

425

-----------

325

25 + 7.50 = 32.5

=> 325/32.5 = 10