Machine A can fill an order of widgets in a hours. Machine B can fill the same order of widgets in b hours.
Machines A and B begin to fill an order of widgets at noon, working together at their respective rates. If a and
b are even integers, is Machine A's rate the same as that of Machine B?
(1) Machines A and B finish the order at exactly 4:48 p.m.
(2) (a + b)2 = 400
Some help on this!
ok here is how...
A can do the work in a hours = > in 1 hr = 1/a
similarly B can do 1/b work in 1 hr
A: we are told that both together completed the work by 4:48 = 4+4/5 hrs = 25/5 hours
24/5 (1/a + 1/b) = 1
a+b / ab = 5/24
=> 24 a + 24 b = 5ab
if both rates are equal... 48a = 5 a ^2
or 5a = 48 => a = 9.6 but given in the question a and b are even integers.. so A and B DO NOT work at the same rate
A is sufficient
B: (a+b)2 = 400 => a+b = 200.....
possible cases a = 100, b = 100... a = 50, b = 150... so cannot say....
hence ans is A