Inversion is not distributive, unlike multiplication. You cannot add the inverses, because 1/(1/x + 1/x) is not equal to (1/1/x+ 1/1/y)=(x+y) what you need to do is multiply by 1, in the form xy/(xy), to get xy/(y+x) Multiplication IS distributive; eg a(b + c) = ab + ac; this is probably why you are...

Think of it like a math problem. Odds of guessing wrong: once: 50% twice: 25% thrice: 12.5% You might be overthinking it. If you're guessing, you're going to get some wrong; you can't beat the odds unless you can make it a little better of a guess. 50/50 is not great odds; but practice, practice pra...

I'm not sure; 10 questions is not a lot to get for free, but $19 isn't too much money to lose if not. If you'd like to try more free questions first, take a look at http://www.testsandtutors.com/course/view.php/GMAT

Each hour the train 10h, where h is the hour number.
hour 1: 10 hour 4: 100 hour 7: 280
hour 2: 30 hour 5: 150 hour 8: 360
hour 3: 60 hour 6: 210 hour 9: 450

It will take 9 hours. You can't simply use an integral, because the speed does not increase smoothly.

at the first church he has N flowers -- which is doubled to 2N -- from which he offers P, leaving 2N-P repeat at the second church, -- double: 2( 2N-P) -- offer P: 2( 2N-P) - P repeat at third church, -- double: 2( 2( 2N-P ) - P) -- offer P: 2( 2( 2N-P ) - P) - P but he has none left! so, 2( 2( 2N-P...