You deposit some money into a bank account paying 8% simple interest per year. You received $500 in interest after 2 years. How much the deposit (principal) was?
Result
The principal was $3125.
Explanation
Find principal by using the formula I=P⋅i⋅t, where I is interest, P is total principal, i is rate of interest per year, and t is total time in years.
In this example I = $500, i = 8% and t = 2 years, so
IPPP=P⋅i⋅t=Ii⋅t=5000.08⋅2=3125
The air force plane travelled for a total of 6.9 hours.
<u>SOLUTION:
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Given, An Air Force plane left Nairobi and flew west at an average speed of 159 mph. A cargo plane left sometime later flying in the same direction at an average speed of 207 mph. After flying for 5.3 hours the cargo plane caught up with the Air Force plane.
We have to find the number of hours the Air Force plane flew before the cargo plane caught up.
Now, we know that, 
For air force plane 
Now, when cargo plane caught the air force plane the distance travelled by the planes will be equal.
So, 
Time taken by air force plane = 6.9 hrs
First, you must know these formula d(e^f(x) = f'(x)e^x dx, e^a+b=e^a.e^b, and d(sinx) = cosxdx, secx = 1/ cosx
(secx)dy/dx=e^(y+sinx), implies <span>dy/dx=cosx .e^(y+sinx), and then
</span>dy=cosx .e^(y+sinx).dx, integdy=integ(cosx .e^(y+sinx).dx, equivalent of
integdy=integ(cosx .e^y.e^sinx)dx, integdy=e^y.integ.(cosx e^sinx)dx, but we know that d(e^sinx) =cosx e^sinx dx,
so integ.d(e^sinx) =integ.cosx e^sinx dx,
and e^sinx + C=integ.cosx e^sinxdx
finally, integdy=e^y.integ.(cosx e^sinx)dx=e^2. (e^sinx) +C
the answer is
y = e^2. (e^sinx) +C, you can check this answer to calculate dy/dx
