Math, asked by chirag6151, 1 year ago

Greg and brian are both at point a (above). Starting at the same time, greg drives to point b while brian drives to point c. Who arrives at his destination first? (1) greg's average speed is 2/3 that of brian's. (2) brian's average speed is 20 miles per hour greater than greg's.

Answers

Answered by rishika79
0

Answer:

Step-by-step explanation:

Greg's speed: sgsg

Distance covered by Greg: DD

Time taken by Greg: tg=Dsgtg=Dsg

Brian's speed sbsb

Distance covered by Greg D2√D2 (Hypotenuse of right isosceles triangle = root(2) times base)

Time taken by Brian tb=D2√sbtb=D2sb

1.

sg=23sbsg=23sb

tg=Dsg=D23sb=3D2sbtg=Dsg=D23sb=3D2sb-------------1

tb=2√Dsbtb=2Dsb----------------2

Comparing 1 and 2:

32>2√32>2. Thus, Greg took relatively more time to reach his destination.

Sufficient.

2.

sb=sg+20sb=sg+20

tb=2√Dsb=2√Dsg+20tb=2Dsb=2Dsg+20

tg=Dsgtg=Dsg

Let's prove opposite of st1:

tb>tgtb>tg

2√Dsg+20>Dsg2Dsg+20>Dsg

2√sg+20>1sg2sg+20>1sg

sg2√>sg+20sg2>sg+20

0.4sg>200.4sg>20

sg>50sg>50

Thus, if greg's speed is approx more than 50, brian would take more time, otherwise greg would take more time.

Hope it helps you...

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