3D set mechanics drill page 87 drill #4 (TV programs)

[chirnonc]

I am having trouble with the constraint that says:

"Each 30 minute program is immediatley followed by a 60 miniute program"

I see the explatnation and I under stand it does not mean
30 60 30 60. But what I don't understand is why can't there be a 30 minute program in slot 3.

Thanks
Anne M

BTW i understand the 3D games better then the plain numbered or relative order ....go figure.

[ManhattanPrepLSAT1]

The last constraint guarantees that the fourth program is 30 minutes. If a 30 minute program were broadcast third, how could we satisfy the third constraint that would require us to broadcast a 60 minute program fourth?

The fourth program could not both be 30 and 60 minutes.

I know it's tricky, but as you see more of these games, it'll become second nature.

[zacharywberg]

Can you explain why the sixth spot has to be 60?

[ManhattanPrepLSAT1]

The constraint that requires that every 30 minute program is immediately followed by a 60 minute program makes it impossible to allow the 6th program to be 30 minutes. Remember, there is no 7th program, so putting a 30 minute program 6th would make it impossible to satisfy the constraint. Since the top row is a binary choice 30min/60min, if it's not 30 minutes, it'll have to be 60 minutes.

Does that make sense?