Unit Rates

Question

The speed of a computer can be expressed in MIPS (million instructions per second). A computer unit used for a satellite movie channel can, on average, process about 650 MIPS. The human brain, in comparison, has a processing power equivalent to 100 million MIPS. About how many satellite movie channel computer units are equivalent to the processing power of the human brain? 

Answer 1

We use the Multiplicative Identity (that is, 1) in order to change units without changing the value.

 

The human brain (note: that is the desired answer) can process approximately:

      100,000,000 MIPS

      (100,000,000 MIPS) * 1

      (100,000,000 MIPS)( (1 movie channel)/(650 MIPS) )      

                             [note: MIPS cancels out, leaving only movie channels]

      153,846 movie channels

         This is about 150,000 movie channels  (for a computer speed of 667 MIPS)

Answer 2

You can reword the question to read "About how many satellite movie channel computer units are equivalent to 100 million MIPS?"  One way to solve is to set up a proportion:

 

 computer units/MIPS    =    1/650    =        x/100,000,000            

    

(Careful! Note that the human brain rate is 100 MILLION MIPS)

 

Solve by cross multiplying then dividing:

 

     650x      =    1 * 100,000,000

 

        x        =    100,000,000 / 650

 

        x        =     153,846

 

You may want to use "about 150,000 satellite movie channel computer units" as your answer since the question asks for an approximation.

 

John