a. 1%

b. 1.11%

c. 3.5%

d. 5%

**Answer:** a. 1%

**Explanation:**

Let original price be 100

Increase of 10% means the price now = 100 + (10% of 100) = Rs. 110

Now decrease of 10% means price now = Rs. 110 - (10% of 110) = 110 - 11 = Rs. 99

So change in price = 100 - 99 = Re. 1

**1 is how much percent of 100? It is 1%**

So change in price is 1%.

a. 12.5%

b. 20%

c. 25%

d. 50%

**Answer:** b. 20%

**Explanation:**

Let us assume her consumption was 1 kg at a butter price of Rs 100.

Current expense = 1 x 100 = Rs. 100

New price = 125% of Rs. 100 = Rs. 125

**What would be new consumption 'C' for expenses to stay same?**

C x 125 = 100

C= 0.8kg

So, new consumption is 80% of the old i.e. it is **20%** less than old consumption.

Tip:

For such questions -

Always assume the price of unit quantity (1 kg) as a whole, easy to solve number, preferably 100 (because that is how we talk about percentages - 100%, 85%....so on)

a. 100

b. 150

c. 200

d. 250

**Answer:** b. 150

**Explanation:**

Let maximum marks be M

To pass = 40% of M = | 40M |

100 |

Hence, 20 + 40 = | 40M |

100 |

What were the maximum marks required for the exam?

a. 200

b. 350

c. 400

d. 500

**Answer:** a. 200

**Explanation:**

Maximum marks = M

IMPORTANT - In both cases minimum marks are the same

A gets 10% of M and fails by 30 marks

∴ | 10M | + 30 = minimum marks |

100 |

∴ | 40M | - 30 = minimum marks |

100 |

∴ | 10M | + 30 = | 40M | - 30 |

100 | 100 |

∴ 30 + 30 = | 40M | - | 10M |

100 | 100 |

∴ | 30M | = 60 |

100 |

a. Rs. 1.5

b. Rs. 2.5

c. Rs. 4.5

d. Rs. 5

**Answer:** b. Rs. 2.5

**Explanation:**

20% subsidy price means new price = 0.8P

Let us assume that people buy A kg rice in Rs. 100.

With 20% decrease in price, people will buy (A+10) kg rice in Rs. 100.

Expense = Rs. 100 = Price of rice x Quantity of rice

Since, expense is same, we can say that

A x P = (A+10) x 0.8P

∴ A = 0.8A + 8 --------------- (Cancelling 'P' on both sides)

∴ A = 40

Price of rice = | 100 | = Rs. 2.5 per kg. |

40 |