A plane takes off from a hill at 750 meters above sea level and lands

Question

A plane takes off from a hill at 750 meters above sea level and lands some time later in a town located at 50 meters below sea level. During the first part of its flight, the plane gained height at a rate of 50 meters per minute but then it started to descend at a rate of 20 meters per minute. The duration of the first part of the flight was what percent of the total flight time?

1. The duration of the descent is known.
 2. The total flight time is known.

* Statement (1) ALONE is sufficient, but Statement (2) ALONE is not sufficient
 * Statement (2) ALONE is sufficient, but Statement (1) ALONE is not sufficient
 * BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient
 * EACH statement ALONE is sufficient
 * Statements (1) and (2) TOGETHER are NOT sufficient

gurpreetsingh · Answer

IMO D

For the 1st part

Initial height = 750, after one minute = 750 = 50..after x minute = 750+ 50x = H1

for the descend part... initial height = H1, after y minute = H1-20y = 50

=> 50 = 750 +50x -20y
=> 2y-5x = 75

we need to find  \frac{x*100}{x+y} 
Statement 1: y is given, we can find x, thus sufficient.
Statement 2: x+y is given, using both the equations we can find x, thus sufficient.

Thus D..what is the source and OA?

vittarr · Answer

hope will help:

1)  If we know the duration of the descent  say X => the plane landing made a distance of 50X => a distance of the first flight “UP” was 50X – (750+50) = 50X – 800=> duration of the first part of the flight was distance/speed = (50X – 800)/20 = 2.5X - 40=> duration of the first part of the flight was (2.5X – 40)/  = (2.5X – 40)/(3.5X – 40) percent of the total flight time
 2)  Let X (given) is the total flight time and lt Y is the first part flight time => 50Y - first part (AB) and 20*(X-Y) – second (BC)we know that BC-AB=750+50 => 20(X-Y) – 50Y = 800 => Y = (2X-80)/7=> duration of the first part of the flight was Y/X = (2X-80)/7X percent of the total flight time 
Thus the answer is  D

temp33 · Answer

IMO D

Solution:

The question gives mentions that the plane rises at 50 mts/min and descends at 20 mts/min. And it started from +750 and ended up at +50. 
So the difference in height is 700 without the height differences it went up and down.

Statement 1: The duration of the descent is known.
If we know the duration, the time it went up and down can b respectively calculated by hit and trial method
 HENCE SUFFICIENT.

Statement 2: The total flight time is known.
Since, we know the total time we can again calculate using equation the time it went up and time it went down.
 HENCE SUFFICIENT again.

Thus, answer is D.

Subanta · Answer

it started from +750 and ended up at    -50

bumpbot · Answer

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A plane takes off from a hill at 750 meters above sea level and lands

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