a. 13 days

b. 36 days

c. 52 days

d. 72 days

**Answer:** d. 72 days

**Explanation:**

Let work done by Ram in 1 day = | 1 | & by Shyam in 1 day = | 1 |

R | S |

Both complete work in 24 days. So in 1 day, together they complete = | 1 | = | 1 | + | 1 |

24 | R | S |

For 20 days both work together, so work done by them = 20 | 1 | + | 1 | = | 5 |

R | S | 6 |

Remaining work 1 - | 5 | = | 1 | is done by Ram alone in 6 days |

6 | 6 |

Work done by Ram in 6 days = | 1 | = 6 | 1 | |

6 | R |

∴ | 1 | + | 1 | = | 1 |

36 | S | 24 |

a. 20 days

b. 24 days

c. 25 days

d. 40 days

**Answer:** a. 20 days

**Explanation:**

Tip:

Men = M; Days = D; Time/Hours = T; Work = W

**M _{1}D_{1}T_{1}W_{2} = M_{2}D_{2}T_{2}W_{1}**

1 child binds half the number of books bound by 1 adult

∴ 1 adult = 2 children

Take work done = 1

∴ (20 adults + 16 children) x 10 days x 1 = (8 adults + 12 children) x ? days x 1

Remember - Convert either all adults to children or all children to adults.

∴ 56 children x 10 days x 1 = 28 children x ? days x 1

a. | 7 | times more efficient |

15 |

b. | 7 | times more efficient |

12 |

c. | 3 | times more efficient |

4 |

d. | 4 | times more efficient |

3 |

Answer: d. | 4 | times more efficient |

3 |

Tip:

Men = M; Days = D; Time/Hours = T; Work = W

**M _{1}D_{1}T_{1}W_{2} = M_{2}D_{2}T_{2}W_{1}**

Let the former type be E times efficient.

So, 1 former type pump = E x latter type pumps

So 1F = E x L

∴ 12F x 18 hours x 400 = 16L x 24 hours x 300

∴ (12 x E x L) x 18 x 400 = 16 L x 24 x 300 ------------------> Put value of F i.e. 1F

∴ E = | 4 | = these many times more efficient |

3 |

a. 45

b. 55

c. 100

d. 150

**Answer:** a. 45

**Explanation:**

Tip:

Men = M; Days = D; Time/Hours = T; Work = W

**M _{1}D_{1}T_{1}W_{2} = M_{2}D_{2}T_{2}W_{1}**

Remaining work = 1 - | 1 | = | 2 |

3 | 3 |

Thus (75+E) employees complete | 2 | work in 50 hours. |

3 |

∴ 75 employees x 40 hours x | 2 | = (75 + E) x 50 hours x | 1 |

3 | 3 |

a. 24 days

b. 36 days

c. 42 days

d. 48 days

**Answer:** d. 48 days

**Explanation:**

Let each tree take T amount of water every day.

So 72 trees take 72T water in one day.

With 10% reduction each tree will consume | 90T | amount each day |

100 |

So 90 Trees take 90 | 90T | amount in one day |

100 |

∴ 72T x 54 = 90 x | 90T | x D |

100 |