An ant moved for several seconds and covered 3 mm in the first second and 4 mm more in each successive second than its predecessor. If the ant had covered 1 mm in the first second and 8 mm more in each successive second, then the difference between the path it would cover during the same time and actual path would be more than 6 mm but less than 30 mm. find the time for which the ant moved (in seconds).
A. 5 s
B. 4 s
C. 6 s
D. 2 s
E. None of these
Answer: Option B
Solution (By Examveda Team)
3 + 7 + 11 + 15 + . . . . . (1) 1 + 9 + 17 + 25 + . . . . . (2) The condition is satisfied for the 4 seconds in 2nd journey, ant covered 17 m more than 1st one.This Question Belongs to Arithmetic Ability >> Speed Time And Distance
The first pattern of movement is
3+7+11+15+19+23
The second Pattern of movement is
1+9+17+25+33+41
it is evident that the difference in the net movement b/w the second pattern and the first pattern is more than 6 mm and less than 30mm for a movement of 4 seconds.
as,
in 4 seconds firstpattern= 3+7+11+15=36mm
second pattern= 1+9+17+25=52mm
difference =52-36=16mm which lies b/w 6 & 30
Ans is 4sec(B)
Still don't get it.