Also, since you are asked to give the answer as a percent, the decimal equivalent of 33
%
,
which is 0.33, is incorrect. The percent symbol next to the answer box
indicates that the form of
the answer must be a percent. Entering 0.33 in the box would give the erroneous answer
0.33%.
5. Working
alone at its constant rate, machine
A
produces
k
liters of a chemical in 10 minutes.
Working alone at its constant rate, machine
B
produces
k
liters of the chemical in 15 minutes.
How many minutes
does it take machines
A
and
B
, working simultaneously at their respective
constant rates, to produce
k
liters of the chemical?
minutes
Explanation
Machine
A
produces
liters
per minute, and machine
B
produces
liters per minute. So
when the machines
work simultaneously, the rate at which the chemical is produced is the sum
of
these two rates, which is
liters per minute. To compute the
time required to produce
k
liters at
this rate, divide the amount
k
by the rate to
get
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