Page 63 - Start Up Mathematics_7

2. Three pieces of ropes measuring 0.2 km, 5,005 cm and 1,200 mm respectively are joined end
to end to form a single rope.

(a) How long is the new rope?
(b) Find the cost of the single rope so formed at the rate of ` 15 per metre.
3. Alisha goes to a fruit and vegetable shop. The cost per kg of some of the fruits and vegetables
is displayed.
Onion Potato Radish Apple Mango

` 20 ` 15 ` 7.5 ` 80 ` 50
Find the total amount Alisha has to pay if her purchases are as under:
1.5 kg onions ; 3.6 kg potatoes ; 0.6 kg radish ; 1.2 kg apples

4. A pole vaulter takes a huge leap in order to jump over the bar
placed 9 m above the ground. In the first attempt, he is able to
reach only 7.845 m. In how many attempts will he be able to clear
the bar, if in each successive attempt he improves by 0.231 m.
5. Brass is an alloy that is made by mixing copper and zinc. If 0.6
part of 28.8 g brass plate is copper, how much copper is there
in each piece if the plate is cut into 3 equal pieces?
6. An electric washing machine consumes 1,100 watts per hour.
The company charges ` 13.75 for each kilowatt hour (i.e., 1,000
watts of electricity per hour).
(a) What does it cost to wash clothes for a week, if the washing
machine is used on an average for 2.5 hours every day?
(b) How many hours would a 500 watt ironing press be used continuously to consume
electricity worth ` 38.50?

Values and Life Skills

A car covers 12.55 km of distance in 1 litre of petrol. How much distance will it cover in
36.7 litres of petrol?

What is the importance of pollution norms for a vehicle?

Some NCERT Textbook Questions

1. Which is greater?

(i) 0.5 or 0.05 (ii) 0.7 or 0.5 (iii) 7 or 0.7
(iv) 1.37 or 1.49 (v) 2.03 or 2.30 (vi) 0.8 or 0.88

2. Write the place value of 2 in the following decimal numbers:
(i) 2.56 (ii) 21.37 (iii) 10.25 (iv) 9.42 (v) 63.352
3. Dinesh went from place A to place B and from there to place A B
C. A is 7.5 km from B and B is 12.7 km from C. Ayub went
from place A to place D and from there to place C. D is 9.3
km from A and C is 11.8 km from D. Who travelled more
and by how much? D C

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