2 ps problems

[xcise_science]

Please shed some light on these.

thanks

[Suyog]

1.
A + B = 6/5; Time taken, 1/(6/5) = 5/6 ........ I
B + C = 3/2; Time taken, 1/(3/2) = 2/3 ........ II
A + C = 2; Time taken = 1/2 ....................... III

Adding I, II and III

2(A + B + C) = 5/6 + 4/6 + 3/6 = 12/6 = 2
hence, A + B + C = 1

Ans E.

2.
200, 6 ounce of juice will be 1200 ounce.
To prepare the juice 1 can of concentrate and 3 cans of water is taken.
So to prepare 1200 ounces of juice 300 ounce of concentrate and 900 ounce of water will be required and we have 12 ounce cans of concentrate.

So,
300/12 = 25

Ans A.

[xcise_science]

hi,
I'm still unclear on the rate question.

Yes, the combined rate for ABC = 2, but how is the (answer) Time=1, if the total work (tank filled) = 1?

thanks

[Suyog]

Check L.H.S

A + B + B + C + A + C = 2
2( A+ B + C) = 2
So, A+ B + C = 1
Hope its clear now...

[xcise_science]

No, not really.

I mean, I see the math that you're doing, but I just don't understand why.
Does that make sense?