a man walks from his house to his daught's school at a speed of 3km/hr and returs at speed of 4 km/hr.if he takes 21 minutes for the total journey, find the distance between his house and the school?
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Let us say the distance to school from home is S km
time taken for going to school from home = S/3 hours
time taken for retuning home = S /4 hours
Total journey time : S/3+S/4 = 7S/12 hours
given this is = 21 minutes = 21 / 60 hours
So 7 S / 12 = 21 / 60
S = 21 * 12 / 60 * 7 = 0.6 km = 600 meters
time taken for going to school from home = S/3 hours
time taken for retuning home = S /4 hours
Total journey time : S/3+S/4 = 7S/12 hours
given this is = 21 minutes = 21 / 60 hours
So 7 S / 12 = 21 / 60
S = 21 * 12 / 60 * 7 = 0.6 km = 600 meters
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