Question

6. A man takes 1 h 20 min to cover a distance of 8 km.
(i) How far does he go in 30 s? (ii) How much time will he take to walk 6.5 km?
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Answer 1

i) 1 hr 20 mins = 60*60 + 20*60  = 60 (60+20) = 60 * 80 = 4800 seconds

as, 8 km = 4800 secs

so, 1 second=  8/4800 = 1/600 km

therefore 30 secs=  1/600 * 30 = 1/60*3 = 3/60 = 1/20km

now,

since 1/20 = 5/100

5/100 km= 0.05 km

hence, the man can go 0.05 km far in 30 secs

ii) 1 second = 1/600 km

   1 km= 1/ (1/600) = (1*600)/ 1 = 600 seconds

now, 600 seconds= 600/60 = 10 mins

so, the man will take 10 mins to walk 1 km

now, 10* 6.5= 65

hence, the man will take 65 mins to walk 6.5 km