Question

A car travels a distance of 258 km in 3 hours 35 minutes. What is the speed of the car?

Answer 1

Hint: First convert the time taken by a car in hours by dividing the minutes part by 60. Now substitute the value of distance and time in the formula $Speed=\dfrac{Distance}{Time}$. After that do the calculation to get the speed of the car.

Complete step by step answer:
Given: Distance travelled by car = 258 km
Time is taken by a car = 3 hours 35 minutes
Let the speed of the car be $S$.
To find the speed of the car, the time taken 3 hours 35 minutes must be converted into hours.
To convert the minutes into hours, divide the minutes by 60,
$\Rightarrow 3 hr \, 35 min = 3+\dfrac{35}{60}$
Canceling out the common factor,
$\Rightarrow 3 hr \, 35 min = 3+\dfrac{7}{12}$
Taking LCM and add then add the number in the numerator,
$\Rightarrow 3 hr \, 35 min = \dfrac{43}{12}$
So, the time taken by the car is $\dfrac{43}{12}$ hours.
The formula to calculate the speed is,
$Speed=\dfrac{Distance}{Time}$
Substituting the values of distance and time,
$\Rightarrow S=\dfrac{258}{\dfrac{43}{12}}$
Moving $12$ to the numerator,
$\Rightarrow S=\dfrac{258\times 12}{43}$
Canceling out the common factors,
$\Rightarrow S=6\times 12$
Multiplying the terms,
$\Rightarrow S=72km/h$

Hence, the speed of the car is 72 km/h.

Note:
The students are likely to make mistakes in questions that have units in a different form. Students are advised to use common conversions first to convert all the values in the same unit and then do calculations. Then change back the units into the original form.
This kind of question in Math falls under the “Algebra” category.
Algebra comes from a Latin variant of the Arabic word al-jabr, it came from the book’s title “Hidab al- jabr w'al-muqubala” by a mathematician from Arab-Mohammed ibn-Musa al-Khowarizmi in 825 A.D. If you still don’t think that Algebra is not an important subject, you are wrong. It is used in other fields like science, engineering, economics, mathematics, and medicine. The signs of (+) and (-) which prove to be essential elements in performing algebraic equations were discovered in the 16th century. Before that, people use written words to express the functions of addition and subtraction which was a time-consuming process.