4:05 pm very simple just add 20 minutes to the time
Assuming Earth's gravity, the formula for the flight of the particle is:
s(t) = -16t^2 + vt + s = -16t^2 + 144t + 160.
This has a maximum when t = -b/(2a) = -144/[2(-16)] = -144/(-32) = 9/2.
Therefore, the maximum height is s(9/2) = -16(9/2)^2 + 144(9/2) + 160 = 484 feet.
Acute.........................
General Idea:
The volume of cylinder is given by
, where r is the radius and h is the height of the cylinder.
Applying the concept:
Step 1: We need to find the volume of full cylinder with the given dimensions using the formula.
Volume of full cylinder 
Volume of half cylinder 
Step 2: Let x be the number of minutes of filling the sand.
of sand filled every 15 seconds, there are four 15 seconds in a minute.
So volume of sand filled in 1 minute
.
of sand taken out of cylindrical vase every minute.
Net volume of sand filled in 1 minute = Volume of sand filled in the vase in one minute - Volume of sand taken out in 1 minute
Net volume of sand filled in 1 minute
Volume of sand filled in x minutes
.
We need to set up an equation to find the number of minutes need to fill half the volume in cylindrical vase.

Conclusion:
The number of minutes required for the base be half filled with sand is 57
Step-by-step explanation:
Betty including her three friends equals to four people. Between Betty and her 3 friends, the 8 cookies are divided so each if them receive 2 cookies.