Answer:
They will finish in time for Jamal to catch the bus.
Step-by-step explanation:
Jamal agreed to bring four dozen i.e. 48 cupcakes in for sale.
He started icing cupcakes at 7:40 a.m. at a rate of 3 cupcakes per minute up to 7:50 a.m. that is the time when he needs to be out of his house to catch his bus.
So, with in this 10 minutes (7:40 a.m. to 7:50 a.m.) he would be able to make (10 × 3) = 30 cupcakes.
Now, at 7:44 his older sister started icing cupcakes too. she iced them at a rate of 4 cupcakes per minute.
So, in this 6 minutes (7:44 a.m. to 7:50 a.m.) she will be able to make (4 × 6) = 24 cupcakes.
Therefore, in total Jamal will be able to made (30 + 24) = 54 cupcakes.
Since, 54 > 48 so, they will finish in time for Jamal to catch the bus. (Answer)