Bringing back an old one.... Making Toast

[BMAD]

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?

Edited April 16, 2019 by BMAD

[Thalia]

The third piece finishes coming off at 2:26?

[rocdocmac]

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 April 17, 2019 by rocdocmac
numbers corrected

[Freddie]

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

 

[Pirate8]

 

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.

[BMAD]

On 4/17/2019 at 6:02 AM, rocdocmac said:

  Hide contents

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.

 

[rocdocmac]

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?