Problems

[austorior]

I am a freshman so I am just starting to practice. On my first test I only got about 150... And I realized I have a lot of problems I do not how to do. Could anyone be kind enough and help me on some of them? thanks...

the moon's diameter is about 1/4th of earth's. How far is the horizon from a 6 ft tall astronaut on the moon if his eyes are 4in below the top of his head?
___________mi

An insect pest population triples every 25 days. If an insecticide kills 70% of the insects, how often should it be applied to keep the insect population in check?
_______days

At what depth below sea level (a positive number) is the fresh water pressure equal to 250psi? neglect air pressure contributions.
__________ ft

A quarterback throws a 65yd pass caught by a receiver on the run. If the maximum vertical height of the foot ball was 12yds above the release point, what was the football's initial velocity?
________mph

What is the are of triangle given A-S-S (mod edit for obvious reasons)?

And also btw after practicing this test, I felt that using HP33s on crunchers and ti84 on geometry and word problems is a good way to increase speed and accuracy... am I right?

[AuSmith]

1. Pythagorean. Period... and memorizing the radius of the earth.

Picture of the Moon.

Moon Prob.GIF (5.41 KiB) Viewed 1628 times

[unparseable or potentially dangerous latex formula]

2. You want to find how long it takes for the population to reach [unparseable or potentially dangerous latex formula] of the original, so that when you use the insecticide, you multiply by [unparseable or potentially dangerous latex formula] and get back to the original.

[unparseable or potentially dangerous latex formula]

3. At a depth [unparseable or potentially dangerous latex formula] feet below sea level, for every square inch of a surface, there is [unparseable or potentially dangerous latex formula] cubic feet of water resting on it. You have to memorize the weight density of water. [unparseable or potentially dangerous latex formula] kg per cubic meter is easy, and you can convert that to pounds per cubic foot if you want, but to save time you should memorize both that and [unparseable or potentially dangerous latex formula] lbs/cu.ft.

250=(h/144 cu.ft.)(62.4 lbs/cu.ft.) is how many pounds per square inch (we started with a square inch on a surface). Solve for h.

4. Man, I haven't done all this physics stuff in so long. I think there's a formula

[unparseable or potentially dangerous latex formula]

Find [unparseable or potentially dangerous latex formula] and pick your favorite of

[unparseable or potentially dangerous latex formula]
[unparseable or potentially dangerous latex formula]

to solve for [unparseable or potentially dangerous latex formula].

5. The area of a triangle with legs [unparseable or potentially dangerous latex formula] and [unparseable or potentially dangerous latex formula] with included angle [unparseable or potentially dangerous latex formula] is [unparseable or potentially dangerous latex formula].

As for HP vs. TI, it's a longstanding debate. The folks at Klein use TI and they're not poor, but most people prefer HP. I think I might still like HP better on word/geo (except for the occasional problem that becomes a cinch with a TI)... it's really a personal preference.

[stupidityismygam]

I think your formula for the tangent of the angle needs to be reciprocaled, but i never really memorized those formulas...

For the most part (I think), people use HP for crunchers and simple word/geo and a TI when necessary (TI 89 is helpful for calculus and solvers) but in all honesty it doesn't matter in the end.

Looking at the top two teams this year at 5A UIL State (individuals placing 1st, 1st, 3rd, 4th, 5th, 7th) the calculators used were:

Clements: 1st place - 1 HP, 1 TI 84
4rd place - 1 HP, 1 TI 84
5th place - 1 HP, 1 TI 89?

Klein: 1st place - 1 TI 83, 1 TI 89
3rd place - 1 TI 84, 1 TI 89
7th place - 1 TI 86, 1 TI 89

So really you can be successful with whatever just stick to whatever you prefer

[austorior]

well thanks for the explanations, but about the calc usage it leads to another question...
would it help if I switch from hp ti84 combo to hp and ti89 combo?

[AuSmith]

[calcguy]

Here is a correction to the insect pest population problem (09C-27). You want to find how long it takes for the population to reach 1/0.3 of the original, so that when you use insecticide, you multiply by (1 - 0.7) = 0.3 to get back to the original. 3^(t/25) = 1/0.3 → t = 27.4 days.

Note: The original answer key to Test 09C (TMSCA #6) gave the answer 8.12 but the corrected answer is 27.4 days.

[AuSmith]