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1) Six machines working together at constant rate can complete the job in 12 hours. How many machines are needed to complete the same job in 8 hours?
- 2, -3, - 4, -6, -8
OE is 3, could somebody explain this.
2) If 2^x-2^x-2=3(2^13) what is x
- 9, 11, 13, 15, 17
3) a wire of 40 meters is cut in two. one piece is used to form a circle with radius r, the other piece is used for a square. no wire is left. what is the total area in m2 of the circular and the square region in terms of r
b) pr2 +10
c) pr2 +0.25p2r2
d) pr2 +(40-2pr)^2
e) pr2 + (10-0.5pr)^2 (OE)
By the way, did the original formulation of the first question asked "How many ADDITIONAL (or MORE) machines are needed to complete the same job in 8 hours?" Because if it did not, the answer should be 9, not 3.