Another approach: n = 5p + 2 n = 7q + 1 5p + 2 = 7q + 1 5p + 1 = 7q, so for all numbers of q where the number is a multiple of 5 plus 1. Additionally remember for such numbers that the end has to be either 1 or 6 in order for it to be of the form 5p + 1, since all multiples of 5 end in 0 or 5. So to...

area of circular glass = pi*(r-s)^2

area of full thing = pi*(r^2)

area of shaded thingy: pi(2rs-s^2)

= pi*s*(2r-s)

0.6 + (x-7)*0.06 = 0.08x

0.6 + 0.06x - 0.42 = 0.08x

0.18 = 0.02x

x = 9

Should be E. First one is obviously not sufficient. Second one just says A can produce 5 more machines. 5 more machines per what? hour? minute? second?

5c3 * 5c5 + 5c4*5c4 = 10 + 25 = 35

[(0.001)(0.9)]/[(0.999)(0.01)+(0.001)(0.9)] = 0.0826 or 8.26%. This will never be a GMAT question. Simply cannot do it without a calculator. The method behind this;

Truly HIV+/Total HIV +

Well the 68% confidence interval would not tell us much without the total number of recruits right?

No the answer is B. Caveat for statement 1 is 2 or other odd prime