Math, asked by agamsingh7985, 2 days ago

if a car increases it's speed by 10 km/hr then it takes 36 minutes less to cover a distance of 72 km. find the original speed of the car​

Answers

Answered by guptaranjita938
0

Answer:

OriNew time = `(72)/(x + 10)"hr". ` Difference in time = 36 mins. ∴ Original speed = 30km/hr.

Answered by anjumanyasmin
4

Given:

Let the original speed of the car =x km/hrs.

Time taken by it to cover 72km=72/x m

New speed of the car = (x+10)km /hrs.

New time taken by the car to cover 72km=72/x+10 hrs.

As per the given condition, time is reduced by 36 minutes

\begin{array}{l}\therefore \frac{72}{x}-\frac{72}{x+10}=\frac{36}{60} \\\frac{72 x+720-72 x}{x(x+10)}=\frac{3}{5}\end{array}

\begin{array}{l}5 \times 720=3\left(x^{2}+10 x\right) \\1,200=x^{2}+10 x \\x^{2}+10 x-1,200=0 \\x^{2}+40 x-30 x-1,200=0 \\x(x+40)-30(x+40)=0 \\(x-30)(x+40)=0 \\\therefore x=30\end{array}

x=-40 not acceptable

Hence the  original speed of the car​ is 30 km/hrs.

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