The document RD Sharma Solutions - Ex - 10.1, Unitary Method, Class 7, Math Class 7 Notes | EduRev is a part of the Class 7 Course RD Sharma Solutions for Class 7 Mathematics.

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**20 chocolates cost Rs 320. Find the cost of 35 such chocolates.**

Cost of 20 chocolates = Rs. 320

Cost of 1 chocolate = Rs. 320 Ã· 20 = 16

So, cost of 35 chocolates = 35 Ã— 16 = Rs. 560

**The cost of 40 metres of cloth is Rs 200. Find the cost of 50 metres of cloth.**

Cost of 40 metres of cloth = Rs. 200

Therefore, cost of 1 metre of cloth = Rs. 200Ã·40 = Rs. 5200Ã·40 = Rs. 5

Hence, cost of 50 metres of cloth = Rs. 5(50) = Rs. 250

**A car can cover a distance of 522 km on 36 litres of petrol. How far can it travel on 14 litres of petrol?**

Distance covered by the car on 36 litres = 522 km

Distance covered by the car on 1 litre = 522 Ã· 36

Distance covered by the car on 14 litres = (522 Ã· 36) Ã— 14 = 203 km

**Travelling 900 km by rail costs Rs 280. What would be the fare for a journey of 360 km when a person travels by the same class?**

Fare for 900 km of rail travel = Rs. 280

Fare for 1 km = Rs. 280 Ã· 900

Therefore, fare for 360 km = (280 Ã· 900) Ã— 360 = Rs. 112

**If 6 oil tankers can be filled by a pipe in 4 1/212 hours, how long does the pipe take to fill 4 such oil tankers?**

Time taken by the pipe to fill 6 oil tankers = 4 1/2 = 9/2 hours

Time taken to fill 1 oil tanker = 92Ã—16 = 34hours92Ã—16 = 34hours

Therefore, the pipe will be able to fill 4 oil tankers in 34Ã—4 = 3 hours.34Ã—4 = 3 hours.

**3/4 of the salary per month is Rs 600. What is the salary per month?**

Let the salary be Rs. x.

Then, 3/4 of the salary per month = Rs. 600.

That is, (3/4) *x = *600

â‡’ *x *= (4 Ã— 600) Ã· 3 = Rs. 800

So, the salary = Rs. 800.

**The cost of 32 tables is Rs 23520. Find the number of such tables that can be purchased for Rs 51450.**

With Rs. 23520, we can buy 32 tables.

Therefore, with Re. 1, we can buy 3223520 3223520 tables.

Hence, the number of tables that we can purchase with Rs. 51450 = 223520Ã—51450223520Ã—51450 = 70.

**The yield of wheat from 6 hectares is 280 quintals. Find the number of hectares required for a yield of 225 quntals.**

Yield of wheat from 6 hectares = 280 quintals

Yield of wheat from 1 hectare = 280 Ã· 6 = 46.66 quintals

Number of hectares required for a yield of 225 quintals = 225 Ã· 46.66 = 4.8 hectares

So, 4.8 hectares is required for a yield of 225 quintals.

**Fifteen post cards cost Rs 2.25. What will be the cost of 36 post cards? How many postcards can we buy in Rs 45?**

Cost of 15 postcards = Rs. 2.25

Cost of 1 postcard = Rs. 2.25 Ã· 15 = Rs. 0.15

Cost of 36 postcards = 36 Ã— (2.25 Ã· 15) = Rs. 5.4

Number of postcards that can be bought for Rs. 45 = 45 Ã· 0.15 = 300

**A rail journey of 75 km costs Rs 215. How much will a journey of 120 km cost?**

Fare for a rail journey of 75 km = Rs. 215

Fare for 1 km = Rs. 215 Ã· 75 = Rs. 2.86

Fare for 120 km = Rs. 120 Ã— 2.86 = Rs. 343.2

**If the sales tax on a purchase wirth Rs 60 is Rs 4.20. What will be the sales tax on the purchase worth of Rs 150?**

Sales tax on purchase worth Rs. 60 = Rs. 4.20

Sales tax on purchase worth Re. 1 = 4.20 Ã· 60

Therefore, sales tax on purchase worth Rs. 150 = Rs. 150 Ã— (4.20 Ã· 60) = Rs. 10.5.

**52 packets of 12 pencils each, cost Rs 499.20. Find the cost of 65 packets of 10 pencils each.**

Cost of 52 packets of 12 pencils each = Rs. 499.20

Cost of 1 packet of 12 pencils = Rs. 499.20 Ã· 52 = Rs. 9.6

Therefore, cost of 12 pencils = Rs. 9.6

So, cost of 1 pencil = Rs. 9.6 Ã· 12 = Rs. 0.8

Cost of 10 pencils = Rs. 10 Ã— (9.6 Ã· 12) = Rs. 8

Therefore, cost of 1 packet of 10 pencils each = Rs. 8

Hence, cost of 65 packets of 10 pencils each = 65 Ã— Rs. 8 = Rs. 520