Mr. Kumar lives in the eastern part of singapore. he visitshis aged parents who lives 36 km away .every weekend . he findsthat if he increases the average speed of his vehcile by 12 km /hhe could save 9 minutes of his travelling time .Find the speed atwhich he travels before the increase in speed.

Brylee Shepard

Brylee Shepard

Answered question

2022-08-04

Mr. Kumar lives in the eastern part of singapore. he visitshis aged parents who lives 36 km away .every weekend . he findsthat if he increases the average speed of his vehcile by 12 km /hhe could save 9 minutes of his travelling time .Find the speed atwhich he travels before the increase in speed.

Answer & Explanation

afinat4s

afinat4s

Beginner2022-08-05Added 13 answers

Let's call the speed at which he travels before theincrease in speed 'r' and the amount of time it takes him at thisspeed 't'.
Then, using the formula: distance = rate ×time, we have:
36 = r ×t.
Then we are told that if he increases his rate by 12 km/hr hecould save 9 minutes. Thus,
36 = (r+12)(t-9).
Setting these two equal, we have:
rt = (r+12)(t-0.15). *Note that 9 minutes is 0.15hours.
Expanding, we have:
rt = rt - 0.15r + 12t - 1.8.
Subtracting out the rt term and solving for t, we get:
t = 0.0125r + 0.15.
Plugging this into our original equation 36 = rt, wehave:
36 = r(0.0125r+0.15).
Expanding, we see:
36 = 0.0125 r 2 +0.15r.
Moving all the terms to the right side, we have:
0 = 0.0125 r 2 +0.15r-36.
Now, we can apply the quadratic formula to solve for r. Doing this, we find:
r = 48 or -60.
In the context of the problem, the negative solution makes nosense, so r = 48 km/hr.
schnelltcr

schnelltcr

Beginner2022-08-06Added 1 answers

Cheers!

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