GMAT 700+ PS

[farooq]

If x < 12, then it must be true that

(A) - x < -12
(B) - x - 2 < 14
(C) - x + 2 < - 10
(D) x + 2 < 10
(E) x - 2 < 11

On level farmland, two runners leave at the same time from the intersection of two country roads. One runner jogs due north at a constant rate of 8 miles per hour while the second runner jogs due east at a constant rate that is 4 miles per hour faster than the first runner's rate. How far apart, to the nearest mile, will they be after hour?

(A) 6
(B) 7
(C) 8
(D) 12
(E) 14


The rear wheels of a car crossed a certain line 0.5 second after the front wheels crossed the same line. If the centers of the front and rear wheels are 20 feet apart and the car traveled in a straight line at a constant speed, which of the following gives the speed of the car in miles per hour? (5,280 feet = 1 mile)

[satish.nagdev]

If x < 12, then it must be true that

(A) - x < -12
(B) - x - 2 < 14
(C) - x + 2 < - 10
(D) x + 2 < 10
(E) x - 2 < 11

On level farmland, two runners leave at the same time from the intersection of two country roads. One runner jogs due north at a constant rate of 8 miles per hour while the second runner jogs due east at a constant rate that is 4 miles per hour faster than the first runner's rate. How far apart, to the nearest mile, will they be after hour?

(A) 6
(B) 7
(C) 8
(D) 12
(E) 14


The rear wheels of a car crossed a certain line 0.5 second after the front wheels crossed the same line. If the centers of the front and rear wheels are 20 feet apart and the car traveled in a straight line at a constant speed, which of the following gives the speed of the car in miles per hour? (5,280 feet = 1 mile)

for first and second I find E to be proper, for 3rd you've not given answer choices but I was getting around 27 mph

in first one remember to change inequality sign with negation, E leaves valid answer

in second apply pythagorean theorem with 8 and 12 as sides

[papgust]

For Prob#2,

See attachment for figure,

Apply pythagoras theorem -> x^2 (hypotenuse) = 8^2 + 12^2
x^2 = 208
x= 14 (approx)

Answer is E.


Note: Please post 1 question per topic.

[ershovici]

For the 3 problem
Is the answer 50m/h?
reasoning:
0.5s = 20feet - 1s = 40 feet - 1h = 40*3600feet/h
to get miles/h: (40*3600feet/h)/5280 (simplify) - 150/3 = 50m/h

[grockit_jake]

I like to convert to my final units first, but there is no "better" way:

1/2 s = 1/120 minute = 1/7200 hour

20 ft = 20/5280 miles = 1/264 miles

Miles/ hour = 7200/264 = 27.27 mph