practice problems form district 1 2010

[Salvadoramerican]

took a practice test this morning did okay just couldn't do some problems quickly

#31 Betty Lobs drops a tennis ball from a height of 12 meter. Each time it hits th rebounds to a height of 60% find the distance the ball travels after it hits the ground the fourth time?
I know how to this but it takes me too long is their a short way

#49 instantaneous rate of change of the volume of a right circular cone with a radius of 4cm and an altitude twice its radius is K cm^3/cm. Find K.

#53 Herr Gauss has a box that contains the four letters NINE. If he randomly selects one letter at a time and lines them up, what is the probability that the lines up word is NEIN?

#26 A circle with the center C has a radius of 11 in. A chord AB of the circle is * in long. Find the distance from the chor to the center C?

[nsguy1350]

31. [unparseable or potentially dangerous latex formula]

49.
Related rates problem.
altitude = height, so height = 2r.
[unparseable or potentially dangerous latex formula]
[unparseable or potentially dangerous latex formula]

[unparseable or potentially dangerous latex formula].
It doesn't give you dr/dt, and they specify the rate as cm^3/cm, meaning you have you divide dV/dt by dr/dt. Never seen one like that, but hopefully I'm right.

53. [unparseable or potentially dangerous latex formula].
Or, the chance of any arrangement occuring is [unparseable or potentially dangerous latex formula], and then because there are two indistinguishable Ns, you can multiply by 2! to get [unparseable or potentially dangerous latex formula].

26. I believe by setting up your figure, you'll get a perpendicular bisector of the chord running from the center, with the hypotenuse as the radius. Divide the length of the chord by two to get one side, and then the distance can be found using the Pythagorean theorem.