Can some one please explain why the answer to this DS question is D
Is 2^x greater than 100?
ST1 2√x = 8
ST2 2^-x < 0.01
thanks
Is 2^x greater than 100?
ST1 2√x = 8
ST2 2^-x < 0.01
thanks
This one isn't too bad.
2^x > 100 also means that x >= 7. You can do this with logarithms, if you want, or some quick trial-and-error.
(1) give a quick, easy formula to solve for x. X = 16, which is clearly greater than 7. Sufficient.
(2) gives another formula that we have to mess with a bit. 2^-x < 0.01. With the properties of negative exponents, this is 1 / (2^x) < 0.01. Cross-multiply to get 100 < 2^x. Clearly sufficient.
Answer is D.
