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Q:

3x + y = 19  and x + 3y = 1. Find the value of 2x + 2y

A) 20 B) 18
C) 11 D) 10
 
Answer & Explanation Answer: D) 10

Explanation:

To solve a pair of simultaneous equations such as those given we can add or subtract them.

Adding we get 4x + 4y = 20

Therefore 2x + 2y = 10

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Filed Under: Numbers
Exam Prep: GRE

Q:

A train covers a distance in 50 minutes, if it runs at a speed of 48kmph on an average. Find the speed at which the train must run to reduce the time of journey to 40 minutes.

A) 50 km/hr B) 60 km/hr
C) 65 km/hr D) 70 km/hr
 
Answer & Explanation Answer: B) 60 km/hr

Explanation:

We are having time and speed given, so first we will calculate the distance. Then we can get new speed for given time and distance.
Lets solve it.

Time = 50/60 hr = 5/6 hr
Speed = 48 mph
Distance = S*T = 48 * 5/6 = 40 km

New time will be 40 minutes so,
Time = 40/60 hr = 2/3 hr
Now we know,
Speed = Distance/Time
New speed = 40*3/2 kmph = 60kmph

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Filed Under: Time and Distance
Exam Prep: GRE

Q:

Jack takes 20 minutes to jog around the race course one time, and 25 minutes to jog around a second time. What is his average speed in miles per hour for the whole jog if the course is 3 miles long?

A) 6 B) 8
C) 9 D) 10
 
Answer & Explanation Answer: B) 8

Explanation:

Average speed = total distance / total time

Total distance covered = 6 miles; total time = 45 minutes = 0.75 hours

Average speed = 6/ 0.75 = 8 miles/hour

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Filed Under: Height and Distance
Exam Prep: GRE

Q:

The number of degrees that the hour hand of a clock moves through between noon and 2.30 in the afternoon of the same day is

A) 720 B) 180
C) 75 D) 65
 
Answer & Explanation Answer: C) 75

Explanation:

The hour hand moves from pointing to 12 to pointing to half way between 2 and 3. The angle covered between each hour marking on the clock is 360/12 = 30. Since the hand has covered 2.5 of these divisions the angle moved through is 75.

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Filed Under: Time and Distance
Exam Prep: GRE

Q:

x = y - (50/y), where x and y are both > 0 

If the value of y is doubled in the equation above, the value of x will

A) decrease B) stay the same
C) increase four fold D) increase to more than double
 
Answer & Explanation Answer: D) increase to more than double

Explanation:

The best approach is to pick a number that satisfies the rules that x and y are greater than 0. So for example you could choose 25 for y.

The value of x before doubling is then 25 - 50/25 = 23

The value after doubling y will be 50 - 50/50 = 49, which is more than double.

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Filed Under: Numbers
Exam Prep: GRE

Q:

Which of the following could not be the lengths of the sides of a right angled triangle?

A) 3, 4, 5 B) 5, 12, 13
C) 8, 15, 17 D) 12, 15, 18
 
Answer & Explanation Answer: D) 12, 15, 18

Explanation:

Using Pythagoras theorem we can see that 122 + 152 is not equal to 182
Neither is 102 + 242 = 252

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Filed Under: Ratios and Proportions
Exam Prep: GRE

Q:

The number 0.127 is how much greater than 1/8 ?

A) 1/100 B) 1/1500
C) 1/2 D) 1/500
 
Answer & Explanation Answer: D) 1/500

Explanation:

0.127 expressed as a fraction = 127/1000

1/8 can also be expressed as (1 x 125) / (8 x 125) = 125/1000

The difference is 2/1000, which is 1/500

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Filed Under: Decimal Fractions
Exam Prep: GRE

Q:

If V = 12R / (r + R) , then R =

A) Vr / (12 - V) B) Vr + (V /12 )
C) V D) V / (r - 12 )
 
Answer & Explanation Answer: A) Vr / (12 - V)

Explanation:

We have to rearrange the equation to make R the subject.

Start by cross multiplying by (r + R); V (r + R) = 12R

Multiply out the bracket Vr + VR = 12R

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Filed Under: Numbers
Exam Prep: GRE