A copy machine makes

1 answer:

4 0

$\bf \begin{array}{ccllll}
copies&minutes\\
\textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\
36&1\\
189&x
\end{array}\implies \cfrac{36}{189}=\cfrac{1}{x}$

solve for "x"

You might be interested in

A junk box in your room contains fourteen old batteries, seven of which are totally dead. You start picking batteries one at a

MrMuchimi

Answer:

A junk box in your room contains fourteen old batteries, seven of which are totally dead.

So, number of good batteries = $14-7=7$

a) The first two you choose are both good.

There is a 7/14 chance that we will pick a good battery.

Now there are 13 batteries left and out of that there are only 6 good ones remaining, so this becomes 6/13.

So, combined probability is = $\frac{7}{14}\times \frac{6}{13}$

= 0.23

b) At least one of the first three works.

$\frac{7}{14} \times \frac{6}{13} \times \frac{5}{12} =0.096$

And at least one is good battery, we get : $1-0.096=0.904$

c) The first four you pick all work.

There is a probability of 7/14 for the first one to work, 6/13 for the second, 5/12 for the third and 4/11 when the fourth is good, combined we get by multiplying all:

$\frac{7}{14}\times \frac{6}{13}\times \frac{5}{12}\times \frac{4}{11}=0.0344$