It takes machine A x hours to manufacture a deck of cards that machine B can manufacture in 1/x hours. If machine A operates alone for y hours and is then joined by machine B until 100 decks are finished, for how long will the two machines operate simultaneously?
(100y – x)/(x^2 + 1)
(100x – y)/(x^2 + 1)
(100y – x^3 – x)(x^2 + 1)
(100y – x^2y – y)(x^2 + 1)
100x/(x^2 + 1)
Nice question that I came across. Thought of posting it here. Will post OA later.
I did VICs prolly not the quickest way since it took me bout 4min
A B ---> rates will equal A: 1/x B: x
R 1/x x
T x 1/x
D 1 1
For me I couldnt figure out how to do this w/ the variables so...
A works for 10 hrs at rate of 1/2 (1 deck every 2hrs) so A makes 5 decks.
now B comes in and there is 95 decks remaining. Find the combined rate
1/x+x/1 or 1/2+2=5/2decks/2hrs. (total rate)
use T=D/R 95/5/2= 38hrs
Ok now is where it begins to take a long time... plug in x and y into the answer choices.
E doesnt work, D is ugly and will take awhile to compute w/ the numbers I chose (come back to this if you exhausted the rest of the answers), C doesnt work,
A doesnt work. I went w/ B since I was just bought to cross 4min