Veronica lives in North Dakota and pays 5% in sales tax. She just bought $90 in groceries, but $35 worth of those groceries were
2 answers:
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Answer:
a) For the 90% confidence interval the value of and
, with that value we can find the quantile required for the interval in the t distribution with df =3. And we can use the folloiwng excel code: "=T.INV(0.05,3)" and we got:
b) For the 99% confidence interval the value of and
, with that value we can find the quantile required for the interval in the t distribution with df =106. And we can use the folloiwng excel code: "=T.INV(0.005,106)" and we got:
Step-by-step explanation:
Previous concepts
The t distribution (Student’s t-distribution) is a "probability distribution that is used to estimate population parameters when the sample size is small (n<30) or when the population variance is unknown".
The shape of the t distribution is determined by its degrees of freedom and when the degrees of freedom increase the t distirbution becomes a normal distribution approximately.
The degrees of freedom represent "the number of independent observations in a set of data. For example if we estimate a mean score from a single sample, the number of independent observations would be equal to the sample size minus one."
Solution to the problem
Part a
For the 90% confidence interval the value of and
, with that value we can find the quantile required for the interval in the t distribution with df =3. And we can use the folloiwng excel code: "=T.INV(0.05,3)" and we got:
Part b
For the 99% confidence interval the value of and
, with that value we can find the quantile required for the interval in the t distribution with df =106. And we can use the folloiwng excel code: "=T.INV(0.005,106)" and we got:
Answer:
sedan = 26 miles/gallon
truck = 17 miles/gallon
Step-by-step explanation:
try to write the text in mathematical format as a system of equations
t=truck s=sedan
first equation can be written as
t= (181-5s)/3
we can use it in the second equation and rewrite it as
7[(181-5s)/3]+6s = 275
7(181/3 -5/3s) + 6s = 275
1267/3 - 35/3s + 6s = 275
-35/3s + 18/3s = 275-1267/3
-35/3s + 18/3s = 825/3 - 1267/3
-35s + 18s = 825 -1267
-17s = -442 s = 442/17 = 26 sedan has an average of 26 miles/gallon
we use this value of s in the first equation
3t + 5*26=181 3t=181-130 t= 51/3 = 17 truck has an average of 17 miles/gallon