An air conditioner can coo the hall in 12 minutes while another takes 15 minutes to cool under similar conditions. if both air conditioners are switched on at same instance then how long will it take to cool the room?
Choose the correct choice from the following options:
A) about 7 minutes
B) about 8 minutes
C) about 9 minutes
D) about 10 minutes
E) about 5 minutes
Take LCM of 12 and 15 = 60   12*5= 
<gadget id="calculator">12*5</gadget>
<output>60</output>
60/ 15*4=60.   So if both are switched on together , room cooled in 60/(5+4)=60/9=6.66 minutes   6.66 can be round to 7 minutes , so about 7 minutes   about 7 minutesNSWER: about 7 minutes
<result>A</result>
An air conditioner can coo the hall in 12 minutes while another takes 15 minutes to cool under similar conditions. if both air conditioners are switched on at same instance then how long will it take to cool the room?