Page 105 - Start Up Mathematics_5

Solution: Length of red ribbon = 3.5 m
Working
Length of green ribbon = 1.25 m 3 . 5 0

Total length of ribbons = 5.25 m + 1 . 2 5
Length of pink ribbon = 5.25 m – (3.5 + 1.25) m 4 . 7 5
4 12
= 5.25 m – 4.75 m 5 . 2 5

= 0.50 m or 50 cm – 4 . 7 5
0 . 5 0

EXERCISE 7.2

1. Tarika bought 2.750 kg of apples, 1.250 kg of grapes, 3.500 kg of mangoes. How many
kilograms of fruits did Tarika buy?

2. Rajiv walked 2.5 km. Then he took a bus and travelled 6.5 km. He has to travel a total
of 11.250 km. How many more kilometres does he have to travel?
3. It rained 3.5 cm on Monday, 2.25 cm on Tuesday and 1.75 cm on Wednesday. How
much did it rain in the 3 days?

4. A carpenter bought a 0.9 m long log of wood. He chopped off 0.7 m of it. How much
log of wood is left?

5. Mrs Nanda needs the following ingredients to make dhokla.
gram flour — 0.250 kg, sugar — .005 kg, salt — .015 kg, curd — .100 kg

What is the total quantity of ingredients needed by her?

6. Sushma wants to make 3.5 L of fruit punch. For this, she has mixed 250 mL of apple
juice, 375 mL of orange juice and 500 mL of pineapple juice. How many millilitres of
mango juice should she add?

Multiplication

Let's understand multiplication of decimal numbers with the help of pictures.

+ + =

3 × 0.2 = 0.2 + 0.2 + 0.2

= 0.6

Multiplication of decimal numbers is similar to that of whole numbers with a difference that
the decimal point is placed appropriately.

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