Some SAT I Math Problems that I don't know how to solve.

Toasti
Fri, 27 Nov 2009 21:35:21 +0000

The car drove at 20mph for 30 minutes, and at 40mph for 15 minutes. Therefore it took 45 minutes for the car to drive 20 miles, so set up a proportion 45/20 = 60/x and solve it to get x = 25, so 25mph.
This question basically wants you to find all the numbers that are multiples of both 6 and 8 and less than 50. 24 and 48 are the only numbers that fulfill this criteria, so C is the correct answer.
The first topping can be paired with any other topping besides itself, giving 5 possible combinations. The second topping can be paired with any other topping besides itself and the first topping, so 4 combinations, and so forth. Add these combinations - 5+4+3+2+1=15, so C.
32 is the middle number out of the possible pressures allowed, so when 32 is subtracted from any of the allowed pressures, the absolute value should not exceed 2, since 32-30=2 and 34-32=2. It should be A.


If you don’t understand the above explanation, just plug in all of the allowed pressures to eliminate the wrong choices. XD