91 is divisible by 7. So, it is not a prime number.

Let number of notes of each denomination be *x*.

Then *x* + 5*x* + 10*x* = 480

16*x* = 480

*x* = 30.

Hence, total number of notes = 3*x* = 90.

Each of the numbers except 14 is an odd number. The number '14' is the only EVEN number.

Speed = | 600 | m/sec. | |

5 x 60 |

= 2 m/sec.

Converting m/sec to km/hr

= | 2 x | 18 | km/hr | ||

5 |

= 7.2 km/hr.

A's 1 day's work = | 1 | ; |

15 |

B's 1 day's work = | 1 | ; |

20 |

(A + B)'s 1 day's work = | 1 | + | 1 | = | 7 | . | ||

15 | 20 | 60 |

(A + B)'s 4 day's work = | 7 | x 4 | = | 7 | . | ||

60 | 15 |

Therefore, Remaining work = | 1 - | 7 | = | 8 | . | ||

15 | 15 |

Let the sum be Rs. *x*. Then,

C.I. = | x | 1 + | 4 | 2 | - x | = | 676 | x | - x | = | 51 | x. | ||||||

100 | 625 | 625 |

S.I. = | x x 4 x 2 | = | 2x | . | ||

100 | 25 |

51x | - | 2x | = 1 | |

625 | 25 |

*x* = 625.

Let the total profit be Rs. 100.

After paying to charity, A's share = Rs. | 95 x | 3 | = Rs. 57. | ||

5 |

If A's share is Rs. 57, total profit = Rs. 100.

If A's share Rs. 855, total profit = | 100 | x 855 | = 1500. | ||

57 |

Let the ages of children be *x*, (*x* + 3), (*x* + 6), (*x* + 9) and (*x* + 12) years.

Then, *x* + (*x* + 3) + (*x* + 6) + (*x* + 9) + (*x* + 12) = 50

5*x* = 20

*x* = 4.

Age of the youngest child = *x* = 4 years.

Angle traced by the hour hand in 6 hours = | 360 | x 6 | º | = 180º. | ||

12 |

Perimeter = Distance covered in 8 min. = | 12000 | x 8 | m = 1600 m. | |

60 |

Let length = 3*x* metres and breadth = 2*x* metres.

Then, 2(3*x* + 2*x*) = 1600 or *x* = 160.

Length = 480 m and Breadth = 320 m.

Area = (480 x 320) m^{2} = 153600 m^{2}.