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BMAT section 1 question

hi everyone, just been going through BMAT practice papers and came across this question. Is there a way of doing this quickly and efficiently without having to manually work through the times? Thank you!

I need to make 72 cakes for when my guests visit tomorrow. I make the cakes in batches of 12.
It takes me 40 minutes to prepare each batch and then they need to be in the oven for 25
minutes (during which time I can be working on the next batch). Once they have finished
baking, I need to spend 5 minutes putting the cakes out to cool before the oven is ready for the
next batch. It is now 1pm.
What time should I finish?

A 4:55pm
B 5:00pm
C 5:30pm
D 5:55pm
E 6:00pm
6 batches- 45 minutes worth of time spent on each batch (40 minutes making and 5 minutes cooling). The 25 minutes in the oven can almost be ignored as that is occurring whilst you make the next batch. This gives a total of 4hrs 30 minutes. However, during the baking of the last batch you aren't making a new batch so you would need to add on the 25 minutes spent baking to get a total of 4hrs 55 minutes after 1pm which is D


Answer online:
72 cakes need to be made in 6 batches (72/12=6). Each batch takes 70 mins to make (40 mins
preparing + 25 mins in the oven + 5 mins cooling). Assuming one cannot cool and prepare cakes
simultaneously, 25 mins are saved on each as preparation can begin whilst the previous batch is in
the oven. This time is not saved on batch 1 as there is no previous batch in the oven when preparing
batch 1. Therefore the total cooking time for 6 batches is 420 mins (6*70) minus 125 mins saved
during the baking of the last 5 batches (5*25), which totals to 295 mins, or 4 hours 55 mins. This
gives us an answer of D which is 4 hours 55 mins after 1pm.
Ah I wasn't aware - thank you for the pointer!
Original post by AzureCeleste
6 batches- 45 minutes worth of time spent on each batch (40 minutes making and 5 minutes cooling). The 25 minutes in the oven can almost be ignored as that is occurring whilst you make the next batch. This gives a total of 4hrs 30 minutes. However, during the baking of the last batch you aren't making a new batch so you would need to add on the 25 minutes spent baking to get a total of 4hrs 55 minutes after 1pm which is D


Answer online:
72 cakes need to be made in 6 batches (72/12=6). Each batch takes 70 mins to make (40 mins
preparing + 25 mins in the oven + 5 mins cooling). Assuming one cannot cool and prepare cakes
simultaneously, 25 mins are saved on each as preparation can begin whilst the previous batch is in
the oven. This time is not saved on batch 1 as there is no previous batch in the oven when preparing
batch 1. Therefore the total cooking time for 6 batches is 420 mins (6*70) minus 125 mins saved
during the baking of the last 5 batches (5*25), which totals to 295 mins, or 4 hours 55 mins. This
gives us an answer of D which is 4 hours 55 mins after 1pm.

That was super concise, thank you!

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