Answer:
<h2>n = 8</h2>
Step-by-step explanation:
Given the nth term of an arithmetic sequence to be Tn = a+(n-1)d
a = first term of the sequence
n = number of terms
d = common difference.
Given the first element a = 2 and 22nd to be 14
T22 = a+(22-1)d = 14
a+21d = 14
Substtuting a = 2 into the equation to get d
2+21d = 14
21d = 12
d = 12/21
d = 4/7
The nth term of the sequence given a = 2 and d = 4/7 will be expressed as;
Tn = 2+(n-1)4/7
Given Tn = 6
6 = 2+(n-1)4/7
6 = 2+4/7 n - 4/7
6-2+4/7 = 4/7 n
32/7=4/7 n
32 = 4n
n = 32/4
n = 8
Answer:
16 oranges
Step-by-step explanation:
The ratio of oranges to apples is 4:3 which means that for every four oranges, there are 3 apples.
Since there are 12 apples in the basket, to find the number of oranges, set up a ratio.
4/3 = x/12 (x represents the number of oranges)
Cross multiply.
48 = 3x
Divide by 3.
x = 16
There are 16 oranges in the basket.
Hope that helps.
We assume the lunch prices we observe are drawn from a normal distribution with true mean
and standard deviation 0.68 in dollars.
We average
samples to get
.
The standard deviation of the average (an experiment where we collect 45 samples and average them) is the square root of n times smaller than than the standard deviation of the individual samples. We'll write

Our goal is to come up with a confidence interval (a,b) that we can be 90% sure contains
.
Our interval takes the form of
as
is our best guess at the middle of the interval. We have to find the z that gives us 90% of the area of the bell in the "middle".
Since we're given the standard deviation of the true distribution we don't need a t distribution or anything like that. n=45 is big enough (more than 30 or so) that we can substitute the normal distribution for the t distribution anyway.
Usually the questioner is nice enough to ask for a 95% confidence interval, which by the 68-95-99.7 rule is plus or minus two sigma. Here it's a bit less; we have to look it up.
With the right table or computer we find z that corresponds to a probability p=.90 the integral of the unit normal from -z to z. Unfortunately these tables come in various flavors and we have to convert the probability to suit. Sometimes that's a one sided probability from zero to z. That would be an area aka probability of 0.45 from 0 to z (the "body") or a probability of 0.05 from z to infinity (the "tail"). Often the table is the integral of the bell from -infinity to positive z, so we'd have to find p=0.95 in that table. We know that the answer would be z=2 if our original p had been 95% so we expect a number a bit less than 2, a smaller number of standard deviations to include a bit less of the probability.
We find z=1.65 in the typical table has p=.95 from -infinity to z. So our 90% confidence interval is

in other words a margin of error of
dollars
That's around plus or minus 17 cents.

So, the answer to this problem is
x = 9/2 or
x = 4.5.