A company has two types of machines, type R and type S. Operating at a constant rate, a machine of type R does a certain job in 24 hrs and a machine of type S does the same job in 12 hours. If the company used the same number of each type of machine to do the job in 2 hours, how many machines of type R were used?  Options.
A) A)3
B) B)4
C) C)6
D) D)9
E) E)12
Rate of machine R =1/24   Rate of machine S =1/12   since same no of machines used for R and S to do the same work in 2 hrs   So collective rate needed to finish the work in 2 hrs= 1/2   Let the no of machine be x   So, x/24 +x/12 =1/2   3x/24=1/2   x=24/6= 
<gadget id="calculator">24/6</gadget>
<output>4</output>
4   So no of machine R is 4   Answer 4
<result>B</result>
A company has two types of machines, type R and type S. Operating at a constant rate, a machine of type R does a certain job in 24 hrs and a machine of type S does the same job in 12 hours. If the company used the same number of each type of machine to do the job in 2 hours, how many machines of type R were used?