Lesson 19- Problems Involving Decimals

Objective

At the end of this lesson, students should be able to understand and solve word problems involving decimals.

Decimal word problems are just like any other word problems except that they involve decimal numbers and not whole numbers.

Example 1

Three cylinders weigh 52.4kg, 48.06kg and 63.587kg. What is the total weight of the three cylinders?

Solution

Total implies addition so:

Example 2

Mary bought items from a super market that totalled £18.05. How much change did she get if she paid £20 at the counter?

Solution

Total cost of items = £18.05

Amount paid at counter = £20

Change given = £20 – £18.05

Example 3

If daddy uses 1.65 liters of petrol each day for 12 days, how many liters of petrol did he use all together?

Solution

Liters of petrol used each day = 1.65L

Liters of petrol used in 12 days = 1.65L x 12

Example 4

The product of two numbers is 96.75. If one of the numbers is 2.5, find the other number.

Solution

Product = 96.75

Multiplier = 2.5

Unit 10 Lesson 19: Exercise 1

1. A coil of wire is 76.8m long. How many pieces of wire, each 3.2m long can be cut from the coil?
2. Jim had £24.50; Peter had £12.45 and Jane had £0.50. How much did the little children have all together?
3. A boy gets £1.75 as pocket money for a week. How much money will he get in 4 weeks?
4. A 3800 litre tank was filed to the brim. In 3 months, the water had reduced by 1238.65 liters. How much water is left in the tank?
5. 25 children raised £62.5 for charity. How much did each child raise?
6. Carmen had three £2 notes. She decided to save £2.50. How much did she have to spend?
7. What is the product of 83.27 and 4.8?
8. How many times is 2.4 contained in 40.8?
9. Mum made three cakes weighing 1.4kg, 2.86kg and 1.96kg. What is the total weight of the cakes?
10. A boy bought an electric toy car for £15.50 at a fair and later sold it for £18.20. How much extra money did he make?

 

Answers

Unit 10 Lesson 19: Exercise 2

1. A car travelled at an average speed of 72.24kph on a trip. If the car travelled for hours, how far did it go?
2. On a quiz, Meg scored 95.28% and Tony scored 93.33%. By what percentage did Meg beat Tony?
3. Three boys went on a camping trip. Their baggages weighed 103.95kg. What was the weight of each boy’s baggage if they carried the same weight?
4. An oil barrel when full needs 39.745 litres of oil to fill it up. How many liters of oil does the barrel hold when full?
5. A motorbike travels 9.6km on a litre of petrol. How far will it travel on half litre of petrol?
6. A shop sold £1,854.47 worth of dresses. If they sold 53 dresses altogether, how much was each dress sold at?
7. A book costs £4.50 and a pen costs £1.99. How much will Blair pay for 2 pens and a book?
8. 6 metres of cloth cost £22.5. How much will 15 metres of the same cloth cost?
9. A bag of seeds fills 15 square meters of farmland. How many such bags will fill 187.5 square metres of farmland during planting?
10. A shop bought a material for £6.45 a metre and sold it at £8.70 per metre. How much profit will the shop make for 18 metres of the material?

 

Answers