Question 37809
In your compound interest formula,
P is the principle (5000)
r is the rate (.07)
n is the number of times it compounds (4)
t is the time (variable)

{{{A=P(1+r/n)^nt}}}

Since you start out with $5000 and you want it to double, A will be $10,000.
Now all you need to do is plug the numbers into the formula. 

{{{10000=5000(1+(.07/4))^(4t)}}}
{{{2=(1+.0175)^(4t)}}}
{{{2=1.0175^(4t)}}}

Now to solve for t, you need to use logs. 

{{{log(2)=log(1.0175)^(4t)}}}
{{{log(2)/log(1.0175)=4t}}}
{{{39.9539818154=4t}}}
{{{t=9.988495}}}

Round to the nearest tenth

Answer: {{{highlight(10)}}}years

Hope this helps!