Question

25. Tom and Jerry must stuff and mail 1000

Answer 1

Answer:

Option D. 12 hours

Step-by-step explanation:

Let the work done by Tom to do the job alone = x hours

So per hour work done by Tom = $\frac{1}{x}$

Jerry can do the job alone in the time = 6 hours

Per hour work done by Jerry = $\frac{1}{6}$

Similarly job done by both together in the time = 4 hours

Per hour work done by both together = $\frac{1}{4}$

Now we know,

Per hour work done by both together = per hour work done by Tom + Per hour work don by Jerry

$\frac{1}{4}=\frac{1}{x}+\frac{1}{6}$

$\frac{1}{x}=\frac{1}{4}-\frac{1}{6}$

$\frac{1}{x}=\frac{3-2}{12}$

$\frac{1}{x}=\frac{1}{12}$

x = 12 hours

Option D. will be the answer.

Answer 2

Answer:

12

Step-by-step explanation:

The general formula for this is

Formula

1/t1 + 1/t2 = 1/t_tot

givens

t1 = 6 hours

t2 = x

t_tot = 4 hours

Solution

1/6 + 1/x = 1/4                 Subtract 1/6 from both sides.

1/6-1/6 + 1/x = 1/4 - 1/6   Change to 12 as your common denominator

1/x = 3/12 - 2/12              subtract

1/x = 1/12                         Cross multiply

x = 12

Tom would need 12 hours to do the job alone.