急急急急急急急急急急....有英文數唔識－快遞百科

標題:

急急急急急急急急急急....有英文數唔識

發問:

Mary and Peter take 30 days and 45 days respectively to build the same house. (a)In one day,(i)How much can Mary build?Express the answer in fraction.(ii)How much can Peter build?Express the answer in fraction.(iii)If Mary co-operates with Peter and build the house together,how much can they build?(b) If Mary... 顯示更多 Mary and Peter take 30 days and 45 days respectively to build the same house. (a)In one day, (i)How much can Mary build?Express the answer in fraction. (ii)How much can Peter build?Express the answer in fraction. (iii)If Mary co-operates with Peter and build the house together,how much can they build? (b) If Mary and Peter build the house together, how long do they need to finish the house?

最佳解答:

a. i. Mary can build = 1/30 in one day ii. Peter can build = 1/45 in one day iii. Mary and Peter co-operate and build = 1/30 + 1/45 = 3/90 + 2/90 = 5/90 = 1/18 in one day Let x be the required days So, x(1/18) = 1 x = 1 X 18 x = 18 Therefore, if they build the house together, they will need 18 days to finish the house.

其他解答:

(i)33/89 (ii)12/89 (iii)45 (b)75