A man covered a distance of 3990 km partly by air, partly by sea and the remaining by land. the time spent in air, on sea and on land is in the ratio 1:16:2 and the ratio of average speed is 20:1:3 respectively. if totaln average speed is 42km/hr then the distance covered by sea is_______

A) 1602 KMS

B) 1520 KMS

C) 1620 KMS

D) 1500 KMS

Let the ratio of actual time spent in air, by sea and on land = t : 16t : 2t

 

total time = t + 16t +2t = 19t

 

overall average speed  = ....................(1)

 

from eqn.(1), we get t = 5hrs ;

Hence time spent on air = 5 hr ; time spent by sea = 16×5 = 80 hr ; time spent on land = 2×5 = 10 hr .

 

Let the ratio of actual speed in air, on sea and on land = 20v : v : 3v

 

distance covered in air = 20v×5 = 100v km

distance covered on sea = v×80 = 80v km

distance covered on land = 3v×10 = 30v km

 

total distance 100v+80v+30v = 210v = 3990 km ........................(2)

 

from (2) we get v = 19 km/hr

 

distance covered by sea = 80×19 = 1520 km