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A boy use to walk to school every morning & it takes him 20 min. One day on his way, he realise that he had gotten his H.W notebook at home. He knew that if he continued walking to school at the same speed, he would be there 8 min before the bell. So he went back home for the notebook & arrive the school 10 min after the bell. If he walked all the way with his usual speed, then what fraction of the way to school had he covered till the moment he turned back?
Asked by bhavikaguddu32 | 15 Jul, 2019, 22:07: PM
answered-by-expert Expert Answer
Let d is the distance from home to school.
If he walks from home to school in 20 min, his walking speed ( d/20 )
 
Let x is the distance from home to the turning point on that day he forgotten HW notebook.
 
on that day he hastravelled a distance (2x+d)
 
Since normally he reaches 8 min before school bell ringing time, but on that day he reached 10 min after school bell,
then time taken on that day = 20+8+10 = 38 min.
 
then we have,   (2x+d) / (d/20)  = 38  ...................(1)
 
By dividing Numerator and denominator of LHS of eqn.(1) by d, we get,     2(x/d) + 1 = 38/20 = 19/10 ..........(2)
 
Hence we get the required fraction x/d from eqn.(2) as,   (x/d) = 9/20
Answered by Thiyagarajan K | 16 Jul, 2019, 12:50: PM

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