**Sol: **Ratio of efficiency = 2:1 (A:B)

Ratio of required time = 1:2 (A:B) x:2x

but 2x-x=30

x= 30 and 2x= 60

Now efficiency of A =3.33% and efficiency of B =1.66%

Combined efficiency of A and B together = 5%

time required by A and B working together to finish the work = = 20 days

Note: Efficiency

Efficiency time = Constant Work

Hence, Required time =

whole work is always cosidered as 1, in terms of fraction and 100%, in terms of percentage.

In, general no.of days or hours =

A) 4 days | B) 8 days |

C) 3 days | D) 6 days |

Explanation:

4/10 + 9/x = 1

=> x = 15

Then both can do in

1/10 + 1/15 = 1/6

=> 6 days

A) 2 days | B) 2.5 days |

C) 2.25 days | D) 3 days |

Explanation:

1 man's 1 day work = 1/108

12 men's 6 day's work = 1/9 x 6 = 2/3

Remaining work = 1 - 2/3 = 1/3

16 men's 1 day work = 1/108 x 16 = 4/27

4/27 work is done by them in 1 day.

1/3 work is done by them in 27/4 x 1/3 = 9/4 days.

A) 5 (2/3) | B) 6 (3/4 ) |

C) 4 (1/2) | D) 3 |

Explanation:

Work done by P alone in one day = 1/6th of the total work done by Q alone in one day = 1/3(of that done by P in one day) = 1/3(1/6 of the total) = 1/18 of the total.

A) 14 1/2 days | B) 11 days |

C) 13 1/4 days | D) 12 6/7 days |

Explanation:

Let 'B' alone can do the work in 'x' days

6/30 + 18/x = 1

x = 22.5

1/30 + 1/22.5 = 7/90

=> 90/7 = 12 6/7 days

A) 1/6 | B) 1/3 |

C) 2/3 | D) 1/18 |

Explanation:

K's one day's work = 1/30

L's one day's work = 1/45

(K + L)'s one day's work = 1/30 + 1/45 = 1/18

The part of the work completed in 3 days = 3 (1/18) = 1/6.