Chapter 13: Direct and Inverse Proportions

Questions

1. $4$ people finish a job in $12$ days; how many people for $8$ days?
2. $10$ pens cost $\rupee 250$. Cost of $6$ pens.
3. Car at $60$ km/h takes $3$ h. Time at $45$ km/h.
4. If $12$ workers finish in $9$ days, how many days will $18$ workers take?
5. Cost of $5$ pens is ₹$60$: cost of $8$ pens.
6. A car covers $150$ km at $50$ km/h; time for $240$ km at same speed.
7. At speed $60$ km/h, distance in $3$ h; at $80$ km/h, time for same distance.
8. If $4$ machines fill $200$ bottles in $1$ h, how many bottles will $6$ machines fill?
9. Speed doubles → time?
10. $y \propto x$; $y = 20$ when $x = 5$: $y$ when $x = 8$.

Extra Practice (Optional)

• $5$ kg rice for $\rupee 300$; cost of $8$ kg.
• $6$ men build a wall in $10$ days; $15$ men?
• $3$ boys eat $12$ chapatis in $30$ min; $5$ boys eat $20$?