Any Smart Math People

[keenan87]

Hey guys, I am currently stuck on some math questions (Grade 12) and am wondering if I can get someone's help. My assignment is due very soon and I really need to finish these questions.

The Questions are from both the Trigonometry and Statistics unit. I would really appreciate if someone can help me out by showing me how to do the questions. I know there are tons of smart people out there on CP.

Statistics:
4 marks 1. "When reporting results to head office, Janice was told to make sure that the mean is 100 and the standard deviation is 10. When she calculated these statistical measures, she found the actual standard deviation to be 8.4 and the mean to be 106.5. Explain what Janice has to do before sending in her results to head office"


4 marks 2."Krina works in a call center assisting home-computer users. The average length of a call in her center is 605 seconds. Her last call took only 569 seconds. her manager offers a bonus for calls that are handled efficiently and quickly. If a call is hand;ed more quickly than 95% of calls, a $2 bonus is paid. What is the largest standard deviation for calls that would let Krina's latest call get the bonus? " I don't even know where to begin with this question.

4 marks 3.The probability of exactly 4 people out of 10 having a red ticket at a charity ball is approximately 0.2508. What is the probability, as a percentage, of a random person having a red ticket? (Hint:red or not red)

These are some of real tough questions for me and I will just leave it for Statistics for now.


Greatly appreciate your help

[SteveToms]

I could help, if my brain was not exploding from doing accounting and finance schoolwork for the last 2 days.

If you still need help later today, I'll see if my brain is back working.

[keenan87]

Originally Posted by SteveToms

I could help, if my brain was not exploding from doing accounting and finance schoolwork for the last 2 days.

If you still need help later today, I'll see if my brain is back working.

Thanks

[Flame Of Liberty]

Thank GOD I will never have to open a Statistics textbook ever again.

Whoa that feels good.

This is my only contribution to this thread, sorry

[4X4]

Paging: Banana Pancakes. Isn't he the local math genius?

[Phanuthier]

put the question from words into numbers (i.e. use the z-equation) and the question will look a lot simpler. Q1 and Q3 looks like there is only 1 variable to solve, while Q2 looks to have 2 (but thats just from glancing at it).

good luck

[Bring_Back_Shantz]

Okay, I can tell you q2 pretty easily. It's in white.
But I want you to know that I'm very disappointed in you for not doing your homework yourself, and that you're only hurting yourself by cheating.

You know that for her call to get the bonus it has to be shorter than 95% of calls. So all you have to do is find out what # of standard deviations from the mean the 95 percentile is. You should be able to pull this off of a chart or graph pretty easily.

Let's say it's 3 standard deviations (I think that might actually be right)
Her call was 36 seconds shorter than the average call, so 36/3=12
So the standard deviation would be 12 seconds.

[FlamesPuck12]

For question 3, do you have to solve it algebraically?

[keenan87]

well not algebraically, but somewhat mathematically

[FlamesPuck12]

Is trial and error a valid method for question 3 because if you were to solve it algebraically, you would have to use the Binomial Distribution formula:

x = 4
n = 10
P(4 success) = 0.2508

Using Binomial Distribution formula:
P(x success) = nCx • p^x • (1-p)^(n-x)
0.2508 = 10C4 • p^4 • (1-p)^6

But you don't learn how to solve for p in this case in Math 30P.



Using guess and test with your calculator
Binompdf(n, p, x) = %
Where n is 10
x is 4
% is 0.2508

Correct Answer:
Binompdf(10, 0.4, 4) = 0.2508
40%

[conroy22]

I should really be able to figure these out, but it's the long weekend, my brain has shut off until I have to study tomorrow. For question 1, if you were to take away the highest and lowest value, it may work out to give those numbers? Thats just a guess, I remember my stats prof mentioning about doing that months ago. I should know how to do question 3, I can't think at the moment.

[SebC]

Originally Posted by conroy22

For question 1, if you were to take away the highest and lowest value, it may work out to give those numbers?

No, question 1 is asking you to standardize the marks. If I had more time I'd offer more help, since I won't just give answers.

[FlamesPuck12]

Question 1 is just asking about the relationship between the mean and the standard deviation in a normal distribution.

Mean is the average value of the data.
Standard Deviation is the amount of dispersion in the data.

To reduce the mean, values above the average must be taken out.
To increase the standard deviation, values close to the mean must be taken out.

So take out the values that are above the mean but close to it in order to reduce the mean and increase the standard deviation.

[FlamesPuck12]

For question 2, the goal is to make 569 fit into the first 2.5% on a bell curve.

According to the z-Score table, first 2.5% has the z-Score of -1.96.

μ = 605
x = 569
z = -1.96

Find σ

z-Score Formula:
z = (x - μ) / σ

Rearrange it to:
σ = (x - μ) / z

σ = (569 - 605) / -1.96
σ = 18.3673

[keenan87]

I am sorry guys, I may have not been clear enough. This is a huge assignment I am completing and not just 3 questions. I have done all of the other questions.

i am looking for help as I really dont get where to start with these questions. I am not cheating, just trying to get some help.

[onetwo_threefour]

Originally Posted by FlamesPuck12

Question 1 is just asking about the relationship between the mean and the standard deviation in a normal distribution.

Mean is the average value of the data.
Standard Deviation is the amount of dispersion in the data.

To reduce the mean, values above the average must be taken out.
To increase the standard deviation, values close to the mean must be taken out.

So take out the values that are above the mean but close to it in order to reduce the mean and increase the standard deviation.

Since when is throwing out data points a legitimate method for doing statistics. Clearly from the question he doesn't have data points to eliminate. There is an algebraic method to adjust the mean and standard deviation as mentioned.

[keenan87]

Originally Posted by onetwo_threefour

Since when is throwing out data points a legitimate method for doing statistics. Clearly from the question he doesn't have data points to eliminate. There is an algebraic method to adjust the mean and standard deviation as mentioned.

do you know a correct algebraic way? I would love to see it as I have never seen a question like this before.

[STeeLy]

I can't do stats questions, but I can do some trig questions... if you want to throw those up (if you have any) I'd be more than willing to try and help...

[FlamesPuck12]

Originally Posted by onetwo_threefour

Since when is throwing out data points a legitimate method for doing statistics. Clearly from the question he doesn't have data points to eliminate. There is an algebraic method to adjust the mean and standard deviation as mentioned.

This is Math 30P (Grade 12 Math).
They're only asking for the relationship between the mean and standard deviation in a normal distribution.

The question says: Explain what Janice has to do before sending in her results to head office

Not solve, but explain the relationship between the mean and standard deviation.

Algebraically adjusting the mean and standard deviation isn't part of Math 30 Pure curriculum. (I don't even know if you can adjust mean and standard deviation when the data points aren't given)

[keenan87]

Here are some Trig Questions:
1.sin(Θ) + cos(Θ)cot(Θ)=csc(Θ)
-State any restrictions to the equation

2.What is the exact value of sin^2(pi/6) - 2sin(pi/6)cos(pi/6) + cos^2(-pi/6)
a)2-(square root of 3)
b)(2-(square root of 3))/2
c)(2+(square root of 3))/2
d)2+(square root of 3)

3.If cos(Θ)= -sin(Θ), then sin^2(Θ) is
a)1/4
b)1/2
c)(square root of 2)/2
d)-(square root of 2)/2

5 MARKS 4. Solve sin2y=cos4y for y, where 0<y<360. Hint (cos4y=cos(2y+2y))

5.Find the exact value of cos(8 degrees)cos(38 degrees) +sin(8 degrees)sin(38 degrees)

5 MARKS 6.This is a hard one:
Prove the Identity sin^2(Θ)/(1-cos(Θ)) = (sec(Θ)+1)/sec(Θ)