Ask Me Help Desk - Math & Sciences

statistic math

patii_s_elaniie — Sat, 21 Nov 2009 01:43:27 GMT

identify the null hypothesis, alternative hypothesis, test statistic, p-value, conclusion about the null hypothesis, and final conclusion that adresses the original claim.

various temperature measurements are recorded at different times for a particular city. the mean of 20C is obtained for 40 temperature on 40 different days. assuming that standard deviation equals 1.5C, test the claim that the population mean is 23C. use a 0.05 significance leve.

time 2 rockets collide

rpmacs — Sat, 21 Nov 2009 00:37:02 GMT

In a test of a heat-seeking rocket, the target rocket is launched at 2000 ft/sec and the heat-seeking rocket is launched along the same flight path 12 seconds later at a speed of 3200 ft/sec. Find the times t1 and t2 of flight of the rockets until the heat-seeking rocket destroys the first rocket.

Trtration-part B

nojha1 — Fri, 20 Nov 2009 17:09:44 GMT

A 10.00 mL sample of the water from the holding tank requires 35.47 mL of 8.193 x 10-4 M EDTA to reach the end point. (A) Based on this titration, what is the concentration of lead(II) ions in the holding tank? (B)Suppose a terrorist group sends a letter to the mayor claiming they have dumped 2 tons of lead(II) nitrate into a 500,000 gallons holding tank at a local reservoir. (Have the terrorists been �accurate� as to their claim?) AND, Is the concentration above or below the EPA acceptable level of 15 ppb?

here,
I try to start the problem by writing following equation:
Pb2+(aq) + EDTA2-(aq) <-> PbEDTA(aq)

One of the member with ID PERRITO helped me with second step as,

The number of moles of EDTA = 0.03547 liter X (8.193 x 10-4 moles/Liter)
= 8.193 x 10-4 moles of EDTA
Since, since one mole of EDTA reacts with 1 mole of pb(2+) so, the number of moles of pb in 10.00 ml is also same.

Then, I DID,
number of moles of pb(2+) in 10.00 ml solution = 8.193 x 10-4 moles of pb
So, Molarity or concentration of pb(2+) = (moles/lit)

=8.193 x 10-4 moles of pb/(10.00X10^-3Lit)
= 0.08193 M [pb(2+)]
IS that right? AND
CAN anyone please help me with part B!!

Writing the standard form of this Ellipse.

SintaxGeforce — Fri, 20 Nov 2009 06:02:16 GMT

A) Find the equation for all points for which
the distance to the point (sqrt 3, 1)
plus
the distance to the point (-sqrt 3, -1)
totals 5.
B) What is the rotation of the ellipse you just found from a standard ellipse?
C) What is the equation of that standard ellipse?

A. For A I Use the distance formula
I got a equation like 52x^2-32xysqrt3+84y^2-225=0

B. I got 30 degrees

C. Not sure how to start off. Bring 225 to the left but whats the next step?

Direct Variation

stacksb — Fri, 20 Nov 2009 02:55:15 GMT

Problem:
3y = 4x + 1

Question: Tell whether equation represents a direct variation. If so, identify the constant of variation (k).

I'm trying the help the next door neighbor and it's been too long since I've dealt with algebra. Please help me. How is this solved and what is the answer to the question?

How do you figure out a scientific notation?

mrhotwheeljr — Fri, 20 Nov 2009 02:19:09 GMT

Write each number in scientific notation.

1.) 169,254,700,125

2.) 728

3.) 0.06753

Please explain how to figure each one so I can do them on my own.

Thank you

TEST tommorow

HAMAYUN — Thu, 19 Nov 2009 23:32:53 GMT

10
10x
___________
2
2x

Express weight as afunction of time

rpmacs — Thu, 19 Nov 2009 22:02:03 GMT

A rocket burns up at the rate of 2.5 tons/minute after falling out of orbit into the atmosphere. If the rocket weighed 6000 tons before reentry, express its weight w as a function of the time t, in minutes of reentry.

I believe the answer is w=2.5t

6000/2.5 2.5t/2.5 t=2400

Help please

Theoretical Math

hehma — Thu, 19 Nov 2009 04:31:19 GMT

Here is my question: An absent minded bank teller switched the dollars and cents when he cashed a check for Mr. Spencer, giving him dollars instead of cents, and cents instead of dollars. After buying a 20 cent newspaper, Mr. Spencer discovered that he had left exactly twice as much as his original check. What was the amount of the check?

Quadritic equation Distance time to find speed.

dbillings — Wed, 18 Nov 2009 23:13:36 GMT

Dan boated downstream with the current for 3 miles, then truned around and cam back to his starting point. If the total time was 4 hours and the current was 0.4 mile per hour, what is the speed dan can boat in still water?

chemistry conversions

sonny11 — Wed, 18 Nov 2009 21:49:37 GMT

how many moles are in 15 grams of lithium?

according to the vsepr theory what molecular geometries are associated with AB2?

frankmary2 — Wed, 18 Nov 2009 21:33:14 GMT

i need help, i have no idea.

Matrices finding equation

jordo6889 — Wed, 18 Nov 2009 17:56:24 GMT

Use a system of equations to find the specified equation that passes thru the points (-2,4) (0,6) and (2,0). Solve the system using matrices.

Gaussian elimination method

jordo6889 — Wed, 18 Nov 2009 17:53:34 GMT

Solve the system of equations below by the Gaussian Elimination method.

2x-6y-5z=11

4x-2y-6z=1

2x+4y-z=11

A correct answer

ljs1215 — Wed, 18 Nov 2009 17:01:43 GMT

I'm :confused:I would like to know if I am setting up this equation correctly.

Q - What is the momentum of an automobile weight 9800 N when it is moving at 35 m/s to the south.

This is what I have done -- am I on the right track.

mg - 9800N
vi = 35 m/s
vf = ?

I'm looking for the final velociity?

my equation:

m = w/g = 9800x1000=9.80 E6/9.8 m/s = 1.00E6
= 1.00E6 x 35m/s = 3.5E7 kg m/s2

Will my answer be 3.5E7 kg m/s or is there another part that I have missed.

LJS