Important for :

1

2

B

Amount = simple interest + principal⇒ 9200 = simple interest + 8000

⇒ simple interest = 9200 – 8000

= Rs 1200

if r % be the rate of interest ,

Then from, simple interest = | principal × rate% × time |

100 |

1200 = | 8000 × r × 3 |

100 |

⇒ r = 5%

2% more interest that is 7% interest

simple interest = | 8000 × 7 × 3 |

100 |

= Rs 1680

thus amount he will get is Rs 8000 + Rs 1680 = Rs 9680

Hence, option B is correct.

3

4

5

C

Given that:Simple interest for 10 years = Rs, 500

Therefore, SI for 1 year = Rs, 50

Therefore, SI for 5 years = Rs. 250

Now, if the principal is made four times, the interest will also become four times.

Therefore, SI for next 5 years = Rs, 250 x 4 = Rs, 1000

Hence, total interest after 10 years = 250 + 1000 = Rs, 1250

Therefore, option (C) is correct.