| A boy walking at a speed of 15 km/h reaches his school 20 min late. Next time he increases his speed by 5 km/h but still he late by 5 min. Find the distance of the school from his home. |
A) 5 km
B) 10 km
C) 15 km
D) 20 km
Correct Answer: C
Solution :
| Let the distance \[=\,\,x\] |
| Here, the difference in time \[=20-5=15\min \] |
| \[=\frac{15}{60}=\frac{1}{4}h\] |
| Speed during next journey \[=15+5=20\,\,km/h\] |
| According to the question, |
| \[\frac{x}{5}-\frac{x}{20}=\frac{1}{4}\] |
| \[\Rightarrow \] \[\frac{4x-3x}{60}=\frac{1}{4}\]\[\Rightarrow \]\[x=\frac{60}{4}=15\] |
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