GMAT Math

tuananhbui wrote:Hi everyone,

I am new to the GMAT and find this line in the book: non-integer x non-integer = non-integer

How come this is true? For example 3/2 x 2/3 = 1 (integer)

Many thanks

tuananhbui wrote:Hi Brent,

I attached the part of the book for you. The book is "McGraw-Hill's GMAT, 2013 edition" by James Hasik; Stacey Rudnick; Ryan Hackney.




Also can you look at this other part of the book which leaves me with doubt. I think the answer to the following example should be
P(X or Y) = P(x) + P(Y) - P (X and Y) = 1/5 + 1/8 - (1/5 x 1/8) = 30% ( However, the book says it is 32.5% )

"But what if you want to figure out the probability of event X OR event Y happening? For example,
let's say you live in a city with great public transportation, and either the 37 bus or the 51 bus can take
you to work from the bus stop right in front of your apartment. The 37 bus arrives every 5 minutes and
the 51 bus arrives every 8 minutes. In any given minute that you stand at the bus stop, what is the
probability of a bus arriving that can take you to work? Well, the probability of the 37 bus arriving is
1/5, because it will arrive during 1 minute of every 5 minutes. Similarly, the probability of the 51 bus
arriving is 1/8. But you don't need both buses; either one would do. So you don't multiply; you add. If
you're not very familiar with adding fractions, you can always convert to decimals and add from there.
1/5 is equal to 0.2 and 1/8 is equal to 0.125. (And if you didn't know those off the top of your head, go
back to Chapter 3 to brush up on converting fractions to decimals.) So your addition problem is 0.2 +
0.125, which is 0.325"

I appreciate your help