Problems on H.C.F and L.C.M
A. B. and C. start at the same time in the same direction to run around a circular stadium. A completes a round in 252 seconds, B in 308 seconds and C in 198 seconds.all starting at the same point.
Interval of change = (L.C.M of 48,72,108)sec.=432sec. So, the lights will agin change simultaneously after every 432 seconds i.e,7 min.12sec Hence , next simultaneous change will take place at 8:27:12 hrs.
To express any fraction in simple (small form), we have to find the HCF of numerator and denominator. 1095)1168(1 1095 73)1095(15 1095 ——— 0 HCF of 1095 and 1168 is 73Therefore (1168/73)/(1095/73) = 16/15