Monday
April 21, 2014

Posts by MathGuru


Total # Posts: 1,360

Stats
0.1359 is the area under the normal curve between z = -1 and z = -2 Look at a normal distribution table (z-table) to check.

Statistics
Type I errors result when you reject the null and it's true. Type II errors result when you accept the null and it's false. If you reject the null hypothesis that the subject is guessing and it's true, you have made a Type I error. If you accept the null that the ...

statistics
Standard error of the proportion is: √(pq/n) p = .55 q = 1-p = .45 n = sample size I'll let you take it from here.

statistics
Some notes on finite population correction factor: If the population is small and the sample is large (more than 5% of the small population), use the finite population correction factor. For standard error of the mean, use: sd/√n If you need to adjust for the finite pop...

personal finance
Common stock

Statistics
1. Relationship condition (the two variables must be related) 2. Temporal condition (time order) 3. Lack of other explanation condition (not due to confounding variables, etc.)

statistics
Regression equation: predicted y = a + bx ...where a represents the y-intercept and b the slope. In your equation, b (slope) = 0.0712

Science
If the current is held constant, an increase in voltage will result in an increase in resistance.

Statsistics
Here is a hint: It doesn't matter if the correlation is negative or positive, the closer it is to zero, the weaker the correlation.

stats
Use a confidence interval formula for the data. Here is an example of one for a 95% confidence interval: CI95 = mean ± 1.96 (sd/√n)

statistics
Use a one-sample z-test. Calculate to find the test statistic. Find the critical value using a z-table for .05 significance level for a one-tailed test. The p-value is the actual level of the test statistic and is found using a z-table as well.

science
Velocity = Frequency * Wavelength V = 5 hertz * 10 mm V = ? I'll let you finish.

Statistics PLEASE HELP ME!
You might try this formula: Pr[T ≤ t] = 1 - e^-ht h = reciprocal of the mean t = time Therefore, the reciprocal of 25 is 1/25 or .04 Substituting into the formula: Pr[T ≤ 20] = 1 - e^-.04(20) = 1 - e^-.8 = 1 - .4493 = .5507 Check these calculations.

Statistics
Use confidence interval formulas for proportions. CI95 = p + or - (1.96)(√pq/n) ...where √ = square root, p = x/n, q = 1 - p, and n = sample size. CI90 = p + or - (1.645)(√pq/n) Hint: x = 396, n = 621 Convert all fractions to decimals to work the formulas. I ...

Statistics
Use confidence interval formulas for proportions. CI95 = p + or - (1.96)(√pq/n) ...where √ = square root, p = x/n, q = 1 - p, and n = sample size. Hint: x = 150, n = 240 Convert all fractions to decimals to work the formulas. I hope this will help get you started.

Statistics
I think you are referring to "dummy coding" but you may want to check this.

statistics
You can try a proportional one-sample z-test for this problem. Check a table for the critical value to compare to the test statistic. If the test statistic exceeds the critical value, then reject the null and accept the alternative hypothesis.

Statistics
Use a formula to find sample size. Here is one: n = [(z-value * sd)/E]^2 ...where n = sample size, z-value = 1.96 for 95% confidence, sd = 15.2, E = 3.5, ^2 means squared, and * means to multiply. Plug the values into the formula and finish the calculations. Round your answers...

statistics
Here's one way to do this problem: n = 8 p = .80 q = 1 - p = 1 - .80 = .20 You will need to find P(7) and P(8). Add those values together, then subtract from 1. This will be your probability. You can use a binomial probability table, or calculate by hand using the followin...

Math: Statistics Least squares line
Your least squares line looks okay. Now, to find the ?, use 7 for y in the equation and solve for x. That will be the value you seek. Here's how the equation would look: 7 = .01764x + .00693 I hope this helps.

statistics
Standard deviation = √npq = √[(400)(.5)(.5)] = √(100) = 10 Note: n = sample size, p = .5, q = .5

Statistics
Formula to find sample size: n = [(z-value)^2 * p * q]/E^2 ... where n = sample size, z-value is found using a z-table for 95% confidence, p = .5 (when no value is stated in the problem), q = 1 - p, ^2 means squared, * means to multiply, and E = .04 (4% in the problem). Plug v...

statistics
Use a binomial probability formula or use a binomial probability table. Formula: P(x) = (nCx)(p^x)[q^(n-x)] For a): Find P(0) for none For b): Take 1 - P(0) for at least 1 For c): Find P(6) for all If you use the table, p = .04, n = 6 (sample size), x = the values needed for a...

statistics
Use a confidence interval formula for proportions. CI99 = p + or - (2.58)(√pq/n) ...where √ = square root, p = x/n, q = 1 - p, and n = sample size. Hint: x = 300, n = 375 I hope this will help get you started.

algebra
In a regression equation, substitute the amount for x to solve for y. This will give you the predicted cost for whatever year you choose.

Statistics
Looks like you might be filling in a table for a one-way ANOVA test. Your ANOVA summary table has the following setup: Source.....SS.....df.....MS.....F Between Within Totals Here are a few hints: SS total = SS between + SS within To calculate df between: k - 1 Note: k = numbe...

Biology
Many invertebrates (like earthworms) use a nephridium as their excretory organ.

statistics
Looks like you might be doing a one-way ANOVA test for the data you choose for this project. Your ANOVA summary table should have the following setup: Source.....SS.....df.....MS.....F Between Within Totals If you calculate by hand, here are a few hints: SS total = SS between ...

statistics
Poisson distribution (m = mean): P(x) = e^(-m) m^x / x! Values: x = 3 m = 5 Substitute and calculate.

statistics
You are gaining information about the population. You are estimating the difference in population means by using the difference in the sample means. You also make a few assumptions, such as the populations have the same variance and the populations are normally distributed.

Statistics
See previous post.

Statistics
Looks like an ANOVA design. If there were significant differences, then the test was statistically significant.

Statistics in Psychology
a) Looks like a paired t-test (same subjects are used in a "before and after" scenario). b) Looks like an independent groups t-test (different subjects) c) Looks like a matched pairs t-test (matched based on characteristics like age).

Stats
Poisson distribution (m = mean): P(x) = e^(-m) m^x / x! Values for (a): x = 0, 1 m = 0.63 Substitute and calculate for each x. Add those calculations together for a total probability. Then subtract that value from 1. This will give you the probability of more than one death. F...

Stats
Poisson distribution (m = mean): P(x) = e^(-m) m^x / x! For (a): Take (0.028)(8) = 0.224 (this is the mean). Find P(0) using the above formula. For (b): Take (0.028)(24) = 0.672 (this is the mean). Find P(0) using the above formula. Then subtract that value from 1. This will b...

Statistics 101
Probably the better answer would be "wider" than 90% confidence interval.

Statistics 101
...greater than 90% confidence interval.

Statistics
Try z-scores: z = (x - mean)/sd Substitute the data into the above formula and solve for x. mean = 11.5 sd = 2.7 z = score from the table Use the table to find z-score at the 80th percentile. I'll let you take it from here.

statistics
I'll get you started. Hypotheses: Ho: µ = 12 --> this is the null hypothesis Ha: µ ≠ 12 ---> this is the alternate or alternative hypothesis Note: Null hypothesis always uses an equals sign. The alternate or alternative hypothesis in this case uses ...

Statistics
Substitute 16 for x and solve for tread depth in the equation.

statistics
Use a confidence interval formula for proportions. Here's one example: CI99 = p + or - (2.58)(sqrt of pq/n) ...where sqrt = square root, p = x/n, q = 1 - p, and n = sample size. p = 120/400 q = 280/400 n = 400 Convert all fractions to decimals before using the formula to p...

statistics
I'll get you started. CI90 = p ± (1.645)[√(pq/n)] ...where p = x/n, q = 1 - p, and n = sample size. Note: ± 1.645 represents 90% confidence interval. For p in your problem: 26/40 For q in your problem: 14/40 n = 40 I let you take it from here to calcula...

STAT - Please check answer
You are correct!

STATS
Use z-scores: z = (x - mean)/sd With your data: z = (80.1 - 75.5)/(10.3) = ? I'll let you finish the calculation. Once you have the z-score, check a z-table for the probability. Remember the problem is asking what percent of students have weights "greater than" 8...

Statistics
Using an online calculator, I found the following: 10 data pairs (x,y): ( 10.0 , 7.00 ); ( 8.00 , 6.00 ); ( 9.00 , 11.0 ); ( 6.00 , 4.00 ); ( 5.00 , 5.00 ); ( 3.00 , 7.00 ); ( 7.00 , 4.00 ); ( 2.00 , 5.00 ); ( 4.00 , 6.00 ); ( 1.00 , 4.00 ); Regression equation: Predicted y =...

statistics
CI95 = mean ± 1.96 (sd/√n) CI99 = mean ± 2.58 (sd/√n) With your data: CI95 = 170 ± 1.96 (62.3/√100) CI99 = 170 ± 2.58 (62.3/√100) I'll let you finish the calculations for the confidence intervals.

Science
C. Nephron, villi, alveoli Capillaries in these structures allow the easy transfer of molecules to these tissues.

Statistics
For part a: Use the appropriate hypothesis test for your data. For part b: Cohen's d is the difference between two means divided by a standard deviation. Calculate Cohen's d (d) and the effect-size correlation (r) using the following formulas: d = (M1 - M2) / s r = d /...

Science asap thankies :)
You are welcome!

Science asap thankies :)
Object will sink if buoyant force is less than the weight of the object. Object will move up if buoyant force is greater than the weight of the object. Object will float or stay constant if both equal.

Algebra
Your answers are correct!

Science
The colors indicate temperature and age. Classification is by spectral type. For example: Type.... Color O.... Blue B.... Blue A.... Blue-white F.... White G.... Yellow K.... Orange M.... Red

biostatistics
Use the binomial probability function: P(x) = (nCx)(p^x)[q^(n-x)] n = 17 x = 11 through 17 p = 0.4 q = 1 - p = 0.6 Find P(11) through P(17). Add together for your probability. Note: You can also use a binomial probability function table with the values listed to find the proba...

heart and lungs/cardiorespiratory fitness
Looks OK!

heart and lungs/cardiorespiratory fitness
Looks OK!

Anatomy and Physiology
B. Prophase

Anatomy and Physiology
C. Reduction

science
D. Meiosis

Algebra
Rectangle formulas: Perimeter = 2l + 2w Area = lw Note: l = length of rectangle and w = width of rectangle Let's look at what you know: Perimeter = 10 yds Width = 2 yd Therefore: Perimeter = 2l + 2w 10 = 2l + 2(2) 10 = 2l + 4 Subtract 4 from both sides. 6 = 2l Divide both ...

Algebra 1A
Step 1: Take time to understand the problem and see what you are expected to do. Step 2: Devise a way to translate the problem so you are able to solve it. Step 3: Carry out your plan to solve the problem. Step 4: Look back at the original problem once you solve it and check y...

Statistics
This appears to be a hypothesis test involving inferences concerning two variances. Sample 1 (Girls): n = 21; variance = 100; df = n - 1 = 20 Sample 2 (Boys): n = 25; variance = 169; df = n - 1 = 24 Test statistic = sample 1 variance / sample 2 variance You can use the F-distr...

science
A heterogeneous mixture is when two or more substances are mixed but remain physically separate.

Math
Answer: 7/10 kg of cherries Tiffany: 2/5 kg = 4/10 kg Linda: 4/10 kg - 1/10 kg = 3/10 kg 4/10 kg + 3/10 kg = 7/10 kg I hope this helps.

Small question memorizing help
Yes, it might help you recall the words and their meanings. Here might be another suggestion: the use of mnemonics for recollection of larger pieces of information. Check it out and see if this method is something you can use.

science
Remember that the dependent variable depends on the independent variable. Speed at which the balls fall depends on the height from which the balls are dropped.

Math
Substitute 6 for x and 17 for y: 4(6) + 5(17) = ? I'll let you take it from here.

Chemistry
Correction: First sentence should read "multiply left side by 2 and right side by 3." Sorry for any confusion.

Chemistry
To balance O, multiply left side by 3 and the right side by 2: 2 KClO3 ---> KCl + 3 O2 Now to balance the KCl, you multiply the right side by 2: 2 KClO3 ---> 2 KCl + 3 O2 That should be it!

statistics
If you are running a hypothesis test using a null and an alternate hypothesis, then yes, you compare a test statistic to a critical value to determine whether or not to reject the null. You then draw conclusions on your findings. I hope this helps and is what you were asking.

math
Try to combine like terms. Is the first term supposed to be -3f^2? If so, then 8f^2 - 3f^2 = 5f^2 Is the second term supposed to be 4f? If so, then 4f + 7f = 11f That leaves: -3 + 1 = -2 Putting it all together, you have this: 5f^2 + 11f - 2 (choice c) I hope this helps and is...

science... PLEASE HELP!
How about species?

math
Substitute numbers for x to determine y. Be sure you have enough numbers to graph. For example: if x = -1, then y = 1 and so on.

Algebra 2..
You can try to set it up like long division (to check, multiply): ......-2x^2 + 15x + 25 R 63 ...________________________ x-3)-2x^3 + 21x^2 - 20x - 12 ....-2x^3 + 6x^2 -->subtracting will change signs .....___________ ............15x^2 - 20x ............15x^2 - 45x -->su...

Science
Here is one difference: Photosynthesis: carbon dioxide is absorbed and oxygen is released. Respiration: oxygen is absorbed and carbon dioxide is released.

Health
B is correct!

health
C is correct!

statistics
You can try a proportional one-sample z-test for the first problem since this problem is using proportions. Here's a few hints to get you started: Using a formula for a proportional one-sample z-test with your data included, we have: z = .63 - .50 -->test value (38/60 i...

Statistics
Choose d. None of the other choices are correct. Choice a: should read change alpha from .01 to .05. Choice b: should read change from a two-tailed test to a one-tailed test. Choice c: should read change sample size n = 25 to n = 100.

prelag8
You may be able to produce a technically accurate statistic, but the data used may be biased or perhaps the data analysis may be not be interpreted or represented correctly.

statistics 3.
Here are a few ideas to get you started. First problem: Use a formula to find sample size. Here is one for proportions: n = [(z-value)^2 * p * q]/E^2 ... where n = sample size, z-value is 1.645 (90% confidence interval), p = .5 (when no value is stated), q = 1 - p, ^2 means sq...

statistics 4.
Here are a few ideas to get you started. First problem: Try a one-sample z-test. Formula: z = (sample mean - population mean)/(standard deviation divided by the square root of sample size) Your data: sample mean = 2.6 population mean = 2.5 standard deviation = 0.5 sample size ...

statistics 3.
See your later post.

statistics 4.
See your later post.

Statistics 4
See your later post.

Statistics 3
See your latest post.

Quick Biology help
First question: 1. gene mutation 2. carcinogens Second question: 1. Cancer Check this!

statistics in psychology
Using an online calculator, we have 4 data pairs (x,y): (1,10) (1,8) (2,4) (4,-2) Regression equation: y = a + bx y = 12.3 - 3.67x This is the line of best fit. You can plot the scatter graph using the points above (x,y) to see how close the points are to the regression line....

Statistics 2
Formulas: CI90 = mean ± 1.645 (sd/√n) CI95 = mean ± 1.96 (sd/√n) For the first part, substitute the mean, standard deviation, and sample size into the appropriate formulas to determine the confidence intervals. This will help you answer the questions ...

Statistics
Note: For the second problem, we use the normal approximation to the binomial distribution when finding the mean and standard deviation.

Statistics
Use z-scores. First problem: z = (x - mean)/(sd/√n) Find two z-scores: z = (2.4 - 2.5)/(0.2/√50) = ? z = (2.8 - 2.5)/(0.2/√50) = ? Finish the calculations. Next, check a z-table to find the probability between the two scores. Find mean and standard deviation....

Personal Finance
I would also say A. A single life annuity usually pays the maximum amount while an individual is alive.

statistic
You would need to determine a regression equation for this data. Linear regression determines the best-fitting straight line through the points. A regression equation helps you make predictions for y based on the value of x.

statistic
See your later post.

statistic
If you do this using a calculator, you will have to use the calculator's instructions for finding a regression equation, correlation coefficient (r) and coefficient of determination (r^2).

STATISTICS
How about a? Check this.

sound
...is amplitude. Check this.

Statistics
False. Should read "...the sampling distribution of the mean will be equal to the population mean." (Central Limit Theorem)

Statistics
Formula: z = (x - mean)/(sd/√n) With your data: z = (76 - 70)/(18/√9) = 6/6 = 1 Choice: c

mth-stat-help-plz
How about A)? (Check a z-table. P-value is the actual level of the test statistic.)

math-true/false
Check 9) using z-scores: z = (x - mean)/sd z = (2.40 - 2.04)/0.25 z = 1.44 Using a z-table, probability = 0.0749 Answer: False Check 13) using margin of error: Margin of error = z-value * (sd/√n) 2.00 = 1.645 (10/√n) n is approximately 68 (rounded up) Answer: Maybe...

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