In a race, a car travelled at a speed of 150 kmph. If it had travelled at 180 kmph, it would have completed the race before 3 minutes. Find the length of the track.

A. 12
B. 48
C. 36
D. 42
Explanation:
Married couples = MF MF MF MF
AB CD EF GH
Possible teams = AD CB EB GB
AF CF ED GD
AH CH EH GF S
Since one male can be paired with 3 other female, Total teams = 4×3 = 12.
Team AD can play only with CB,CF,CH,EB,EH,GB,GF(7 teams )
Team AD cannot play with AF, AH, ED and GD
The same will apply with all teams, So number of total matches = 12×7 = 84.
But every match includes 2 teams, so the actual number of matches = 84/2 = 42.