Exercise 12.3

1. If the cost of 7 m of cloth is ₹ 1470, find the cost of 5 m of cloth.

Cost of 7m cloth = Rs

Hence, the cost of 1 m cloth = 14707 = Rs

Cost of 5 m cloth = 210 × 5 = Rs

Hence, the cost of 5 m of cloth is Rs.1050.

2. Ekta earns ₹ 3000 in 10 days. How much will she earn in 30 days?

Money earned by Ekta in 10 days = Rs

Hence, money earned in one day by her will be = 300010 = Rs

Therefore, money earned by Ekta in 30 days = 300 × = Rs.

3. If it has rained 276 mm in the last 3 days, how many cm of rain will fall in one full week (7 days)? Assume that the rain continues to fall at the same rate.

Instructions

4. Cost of 5 kg of wheat is ₹ 91.50.

(a) What will be the cost of 8 kg of wheat?

Let's use the concept of the unitary method.

The cost of 5 kg of wheat = ₹ .

Now, the cost of 1 kg of wheat will be 91.55 = ₹

Therefore, the cost of 8 kg of wheat is 18.3 × 8 = ₹

(b) What quantity of wheat can be purchased in ₹ 183?

Let us calculate the quantity of wheat purchased in ₹183

Quantity of wheat purchased in ₹ 91.50 = kg

Hence, wheat purchased in ₹ 1 = 591.5 kg

Therefore, wheat purchased in ₹ 183 = (591.5) × 183 = kg

Thus, we can say that the cost of 8 kg of wheat is ₹ 146.40, and the quantity of wheat purchased in ₹ 183 is equal to 10 kg.

5. The temperature dropped 15 degree celsius in the last 30 days. If the rate of temperature drop remains the same, how many degrees will the temperature drop in the next ten days?

Temperature drop in 30 days : 15°

So, Temperature drop in 1 day : = 1530 = 12 = °

And Hence, The Temperature drop in 10 days : 10 × 0.5 = °

Hence if the temperature rate remains the same, there will be a drop of 5 degrees in the next 10 days.

6. Shaina pays ₹ 15000 as rent for 3 months. How much does she has to pay for a whole year, if the rent per month remains same?

Rent paid by Shaina in 3 months = ₹

Rent for 1 month = 150003 = ₹

So, rent for 1 year = 5000 × = ₹

Therefore Rent paid by Shaina in 1 year is ₹ 60,000.

7. Cost of 4 dozen bananas is ₹ 180. How many bananas can be purchased for ₹ 90?

Number of bananas bought in ₹ 180 = 4 dozens = 4 × = bananas

Number of bananas bought in ₹ 1 = 481801804

So, number of bananas bought in ₹ 90 = (48180) × 90 = bananas

Therefore, 24 bananas can be purchased for ₹ 90.

8. The weight of 72 books is 9 kg. What is the weight of 40 such books?

Weight of 72 books = 9 kg

Weight of 1 book = 972 = kg

So, weight of 40 books = (18) × 40 = kg

Therefore, Weight of 40 books is 5 kg.

9. A truck requires 108 litres of diesel for covering a distance of 594 km. How much diesel will be required by the truck to cover a distance of 1650 km?

Diesel required for 594 km = litres

Diesel required for 1 km = 108594 = litre

So, diesel required for 1650 km = (211) × 1650 = litres

Therefore, Diesel required by the truck to cover a distance of 1650 km is 300 litres.

10. Raju purchases 10 pens for ₹ 150 and Manish buys 7 pens for ₹ 84. Can you say who got the pens cheaper?

Pens purchased by Raju for ₹ 150 = pens

Cost of 1 pen = 15010 = ₹

Pens purchased by Manish for ₹ 84 = pens

Cost of 1 pen = 847 = ₹

Therefore, the pens purchased by Manish are cheaper than Raju.

Anish made 42 runs in 6 overs and Anup made 63 runs in 7 overs. Who made more runs per over?

Runs made by Anish in 6 overs =

Runs made by Anish in 1 over = 426 =

Runs made by Anup in 7 overs =

Runs made by Anup in 1 over = 637 =

Therefore, Anup scored more runs than Anish.