pp-T1-DS139

[Huang Hsin-Yi]

139. 14556-!-item-!-187;#058&010396
If machine J, working alone at its constant rate, takes 2 minutes to wrap 60 pieces of candy, how many minutes does it take machine K, working alone at its constant rate, to wrap 120 pieces of candy?

(1) Machine K, working alone at its constant rate, takes more than 5 minutes to wrap 60 pieces of candy.

(2) Machines J and K, working together at their respective constant rates, take 1 minute and 30 seconds to wrap 60 pieces of candy.

Ans:B

為什麼 A不行勒?

Machine J speed=60/7 這樣就知道 120pieces 要花多少時間


我猜紅色字部份一定有陷井

[amazingslim]

K機器用超過5分鐘，包60顆糖果
並不是說K比J多用5分鐘

[Huang Hsin-Yi]

謝謝!果真我想錯了