Page 160 - Start Up Mathematics_8 (Non CCE)

3. Ramita cycles to her college at an average speed of 15 km/h. She takes 30 minutes to reach her college.
If she wants to reach her college in 25 minutes, what should be her average speed?
4. In an army camp there is sufficient food for 120 cadets for 24 days. If 48 cadets leave the camp, how
long would the food last?
5. If x and y are in direct variation with each other, fill in the x ... 4 7 ... 12
missing entries. y 10 20 ... 45 ...

Thinking Skills

1. The distance between two cities on a map is 8.4 cm. The map uses 3 cm to represent 16 km. What is the
actual distance between the two cities?
2. 600 soldiers in a fort had enough food for 30 days. After 6 days, some soldiers were sent to another fort
and thus the food lasted for 40 more days. How many soldiers left the fort?
3. 9 men working 6 hours a day earn ` 9,450 per week. What will be the earning per week of 6 men working
8 hours a day?
4. If 8 persons can weave 160 shawls in 5 days, how many shawls will be woven by 3 persons in 14 days?

Values and Life Skills

1. A car uses 20 litres of petrol for a journey of 115 km. How much petrol will be needed for a journey of
345 km? Can you suggest some benefits of the reduced consumption of petrol?
2. An event manager estimates that 5 bottles of juices will be used for making 8 servings of the drink. How
many bottles are required to make 32 servings? What will you prefer juice or an aerated drink? Why?
3. A box of chocolates was distributed among 8 children and each child got 5 chocolates. If this box of
chocolates is distributed among 10 children, how many chocolates will each child get? What is the
importance of equality?
4. A swimming pool can be filled in 24 hours by 5 equal pumps. How many such pumps are required to fill
the pool in 6 hours? What safety precautions should you follow while swimming?
Some NCERT Textbook Questions

1. A photograph of a bacteria enlarged 50,000 times attains a length of 5 cm as shown in the diagram. What
is the actual length of the bacteria? If the photograph is enlarged 20,000 times only, what would be its
enlarged length?
2. In a model of a ship, the mast is 9 cm high, while the mast of the actual ship is 12 m high. If the length
of the ship is 28 cm how long is the model ship?
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3. Suppose 2 kg of sugar contains 9 × 10 crystals. How many sugar crystals are there in (i) 5 kg of sugar?
(ii) 1.2 kg of sugar?
4. In a Television game show, the prize money of ` 1,00,000 is to be divided equally amongst the winners.
Complete the following table and find whether the prize money given to an individual winner is directly
or inversely proportional to the number of winners?

Number of winners 1 2 4 5 8 10 20
Prize of each winner (in `) 1,00,000 50,000 … … … … …
5. A farmer has enough food to feed 20 animals in his cattle for 6 days. How long would the food last if
there were 10 more animals in his cattle?
6. Two persons could fit new windows in a house in 3 days.
(i) One of the persons fell ill before the work started. How long would the job take now?
(ii) How many persons would be needed to fit the windows in one day?

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