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# Bringing back an old one.... Making Toast

## Question

Three slices of bread are to be toasted under a grill. The grill can hold two slices at once but only one side is toasted at a time. It takes 30 seconds to toast one side of a piece of bread, 5 seconds to put a piece in or take a piece out and 3 seconds to turn a piece over. What is the shortest time in which the three slices can be toasted?

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On 4/17/2019 at 6:02 AM, rocdocmac said:
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116 seconds (or possibly even 106 seconds) presuming first two pieces are already in place.

Toasting alone takes 90 seconds for slices numbered 1, 2 and 3 with sides A and B.

Stages: (1) 1A  and 2A under grill (30 sec), followed by (2) 1B and 3A under grill (30 sec); finally (3) 2B and 3B under grill (30 seconds)

Normal additional time for single movements:

End of 1st stage: Slice 1 flipped from 1A to 1B (3 sec), 2A removed (5 sec), 3A inserted (5 sec)

End of 2nd stage: Slice 1 removed (5 sec.), slice 3 flipped from 3A to 3B (3 sec), slice 2 (2B) re-inserted with flip side up (5 sec)

End of 3rd stage: Done

Normal additional time = 26 seconds

Total time = 116 seconds.(1:56)

Exchange in one go:

If one is allowed to do simultaneous movements (exchanging in one switch of 5 sec), 10 seconds can be deducted, i.e. a total time of 106 seconds (1:46)

14 hours ago, Pirate8 said:

 Left side Right side 1-5 A1 in 6-10 B1 in 6-35 A1 toast 11-40 B1 toast 36-38 A flip 41-45 B out 39-68 A2 toast 46-50 C in 69-74 A out 51-80 C1 Toast 75-79 B2 in 81-83 C flip 80-109 B2 toast 84-113 C2 toast 110-114 B out 114-116 C out Manual operations must not overlap.

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The third piece finishes coming off at 2:26?

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Spoiler

116 seconds (or possibly even 106 seconds) presuming first two pieces are already in place.

Toasting alone takes 90 seconds for slices numbered 1, 2 and 3 with sides A and B.

Stages: (1) 1A  and 2A under grill (30 sec), followed by (2) 1B and 3A under grill (30 sec); finally (3) 2B and 3B under grill (30 seconds)

Normal additional time for single movements:

End of 1st stage: Slice 1 flipped from 1A to 1B (3 sec), 2A removed (5 sec), 3A inserted (5 sec)

End of 2nd stage: Slice 1 removed (5 sec.), slice 3 flipped from 3A to 3B (3 sec), slice 2 (2B) re-inserted with flip side up (5 sec)

End of 3rd stage: Done

Normal additional time = 26 seconds

Total time = 116 seconds.(1:56)

Exchange in one go:

If one is allowed to do simultaneous movements (exchanging in one switch of 5 sec), 10 seconds can be deducted, i.e. a total time of 106 seconds (1:46)

Edited by rocdocmac
numbers corrected
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Spoiler

Starting the clock when placing the first two slices into the grill and stopping once the final slice is taken out... I get 2 mins, 39 secs

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 Left side Right side 1-5 A1 in 6-10 B1 in 6-35 A1 toast 11-40 B1 toast 36-38 A flip 41-45 B out 39-68 A2 toast 46-50 C in 69-74 A out 51-80 C1 Toast 75-79 B2 in 81-83 C flip 80-109 B2 toast 84-113 C2 toast 110-114 B out 114-116 C out Manual operations must not overlap.
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On 4/18/2019 at 12:39 AM, Pirate8 said:

 Left side Right side 1-5 A1 in 6-10 B1 in 6-35 A1 toast 11-40 B1 toast 36-38 A flip 41-45 B out 39-68 A2 toast 46-50 C in 69-74 A out 51-80 C1 Toast 75-79 B2 in 81-83 C flip 80-109 B2 toast 84-113 C2 toast 110-114 B out 114-116 C out Manual operations must not overlap.

Shouldn't the last entry (for C out) read 114-118?

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