R
How do you print things on R?
print(x)
A student rolls a fair dice, with sides labeled A, B, C, D, E and F. What is the probability that the dice lands on a vowel?
1/3
what type of test do we use if we want to test difference in means and we don't know population varience?
t-test
what is ei
error term
Find the mean and standard deviation of the following sample:
44, 100, 50, 3, 66, 2
mean:
44.2
standard deviation: 37.7
how do you make a histogram in r
hist(x)
A bag I contains 4 white and 6 black balls while another Bag II contains 4 white and 3 black balls. One ball is drawn at random from one of the bags, and it is found to be black. Find the probability that it was drawn from Bag I
7/12
Suppose you want to test if μ is less than 9 hours. Formulate null and alternative hypotheses to be tested
H0 :μ=120
Ha :μ<120
what does the residual describe?
error in the fit of the model
using a standard normal curve, what is the area within one standard deviation of the mean?
68%
name two advantages of using R
any two of the following:
free, frequently updated, active user community, faster than using spreadsheets, rigorous review process, and sophisticated graphics
Alice has some red balls and some black balls in a bag. Altogether she has 25 balls. Alice picks one ball from the bag. The probability that Alice picks a red ball is x and the probability that Alice picks a black ball is 4x. Work out how many black balls are in the bag.
20
You want to estimate the mean weight of all fish in a river. What should be the size of your sample , so that the 90 % confidence interval for the true population mean weight (μ) will have a margin of error of no more than 5 lb? Assume that the population standard deviation (σ) is 20 lb. Assume also normal distribution of all weights of the fish.
44
what does the Pearson correlation coefficient r measure?
strength of a linear association between two variables
what is the central limit theorem
If you take sufficiently large samples from a population, the samples' means will be normally distributed, even if the population isn't normally distributed
what;s the command for linear regression models?
lm(x)
the probability of a fire is 1%
smoke is fairly common (10%) due to barbecues
90% of dangerous fires make smoke
What is the probability of dangerous Fire when there is Smoke?
9%
what test is used for one sample variance
Chi squared
true or false, a low p means a strong fit?
true
find the area between -1 and 1 on a standard normal curve
0.6827
What is a group of characters called
strings
A band is giving 14 concerts in November 2015. The shows are all in Europe and their tour in Europe involves about 40 locations. How many different schedules are possible? That is, how many different possible combinations of cities are possible when giving 14 shows from a set of 40 cities?
23, 206, 929, 840
A sample of n=56 observations of 02 consumption by adult western fence lizards gave the following statistics:
Mean=249mm3/g/hr
s=24mm3/g/hr
Find the 90% confidence limit for the mean 02 consumption by adult western fence lizards.
(243.63mm3/g/hr,254.36mm3/g/hr)
In multiple linear regression, if we fail to reject the null for a regressor, what do we do next?
remove that data and try again using the remaining variables
in process control, quality is inversely proportional to
variability