Mathematics for IGCSE & O level - Proportion (Section 1 - No. 21)
The time (*t*) to cook a roast is directly proportional to its weight (*w*). If a 2-kg roast takes 1 hour to cook, how long will it take to cook a 3-kg roast?
1.25 hours
1.5 hours
2 hours
3 hours
解释
Time = kw, 1=k*2, thus k=0.5; Time=0.5*3 = 1.5.