ElectricPavlov

When the ball hits the ground, it's height is 0

0 = -16t^2 + 20 t

divide through by 4

-4t^2 + 5t = 0          t(-4t+5) = 0    so t = 0 (when he kicks it)  and  5/4 sec (when it comes back down and hits the ground)

She jumps and initially PASSES the 5 ft deck and comes back down to it:

5 = -16t^2 + 18t    

16t^2 - 18t + 5 = 0     use quadratic formula to find t = 20/32  or  16/32

Since she jumps so quickly initially she jumps PAST 5ft (@ 16/32 sec) and comes back down to the 5 ft level at 20/32 sec

You will need the initial velocity (usually 0) and the velocity at the point you are interested in:

x = xo + vo t + 1/2 a t^2     xo = original position.....ususally 0    t = time   a = accelration of gravity (9.8 m/s^2)

This too you posted a few days ago.....and it too, was answered.

You posted this a few days ago...and it was answered.

123.8 IS a decimal     123 8/10   or 123 4/5 as a fraction.

Arcsin  -  .4382 =  334.01 degrees      205.98 degrees

Each month she will be charged interest...if she does not pay more than this interest her balance will not decrease.

Monthly interest amount 

12000*.18/12 = 180             If she pays up to and including this amount her balance will never go down !

With one cut of 'B'  you can make '13'     .... LOL

According to the Web2.0 calculator on THIS website

5349^3 = 153044523549