Question

in a 1200 kilometre journey man driving speed was 60 km per hour for the last One by fourth of the journey if he completed his journey in 17 hours find the driving speed for the first three fourth of the journey​

Answer 1

The speed for the first three fourth of the journey​ is 75 km per hour.

Step-by-step explanation:

Consider the provided information.

The total distance of the journey was 1200 km.

He cover one fourth of the journey at 60 km per hour.

One fourth of 1200 is: $\frac{1200}{4}=300$

He, cover 300 km with 60 km per hour.

Use the formula:  $Time=\frac{Distance}{Speed}$

$Time=\frac{300}{60}=5$

Therefore, it took 5 hours to cover 300 km.

3/4th of 1200 km is 900.

It took 17 hours to complete his journey and 5 hour to complete 1/4.

It took 17-5=12 hours to complete 3/4 th of his journey.

Therefore, the speed for the first three fourth of the journey is:

$12=\frac{900}{Speed}\\\\Speed=\frac{900}{12}\\\\Speed=75$

Hence, the speed for the first three fourth of the journey​ is 75 km per hour.

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Answer 2

$Total \: distance = 1200 \:km$

$\frac{3}{4} ^{th} \: of \: total \:distance \\= \frac{3}{4} \times 1200 \\= 3 \times 300 = 900\:km$

$\frac{1}{4} ^{th} \: of \: total \:distance \\= \frac{1}{4} \times 1200 \\ = 300\:km$

$Total \: time \: to \: complete \: the \\journey = 17 \: hours$

$i) Speed \: of \: last \: one \: by \: fourth \\of \: the \: journey (s) = 60 \: km/hr$

$Distance = 300 \:km$

$Time = \frac{distance}{speed} \\= \frac{300}{60} \\= 5 \: hours$

$ii ) Distance = 900 \:km$

$time = 17 \: hours - 5 \hours = 12 \:hours$

$Speed \: of \: last \: three \: by \: fourth \\of \: the \: journey (s) = \frac{Distance }{time}\\= \frac{900}{12} \\= 75 \: km/hr$

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