# NCERT Solutions for Class 8th Mathematics

## Chapter 13. Direct and Inverse Proportions

### Exercise 13.1

Exercise 13.1

**Q1. ****Following are the car parking charges near a railway station upto**

**4 hours Rs 60**

**8 hours Rs 100**

**12 hours Rs 140**

**24 hours Rs 180**

**Check if the parking charges are in direct proportion to the parking time.**

**Solution : **

**Q2. A mixture of paint is prepared by mixing 1 part of red pigments with 8 parts of base. In the following table, find the parts of base that need to be added.**

**Q3. ****In Question 2 above, if 1 part of a red pigment requires 75 mL of base, how much red pigment should we mix with 1800 mL of base?**

**Solution: **

**Q4. ****A machine in a soft drink factory fills 840 bottles in six hours. How many bottles will it fill in five hours?**

**Solution: **

**Q5. ****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?**

**Q6. ****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 m, how long is the model ship?**

**Therefore the length of model ship is 21 cm. **

**Q7. ****Suppose 2 kg of sugar contains 9 × 10 ^{6} crystals.**

**How many sugar crystals are there in **

**(i) 5 kg of sugar? **

**(ii) 1.2 kg of sugar?**

**Solution: **

**Q8. ****Rashmi has a road map with a scale of 1 cm representing 18 km. She drives on a road for 72 km. What would be her distance covered in the map?**

**Q9. ****A 5 m 60 cm high vertical pole casts a shadow 3 m 20 cm long. Find at the same time**

**(i) The length of the shadow cast by another pole 10 m 50 cm high **

**(ii) The height of a pole which casts a shadow 5m long.**

**Solution: **

**Q10. ****A loaded truck travels 14 km in 25 minutes. If the speed remains the same, how far can it travel in 5 hours?**

**Solution: **