So first start out by writing an expression for the cost of the child and the adult separately.
Child:
6 + 1r ($6 + $1 per ride)
Adult:
10 + 1.5r ($10 + $1.50 per ride)
to find how much more the adult will spend, just do Adult Expression - Child Expression which will be:
10 + 1.5r - (6 + 1r) just simplify this
For Part B, use your equation from part A where r = 7
2h/15=20 so the answer to h would be h=150
Answer: x = (cd + by) / a
Working out:
(ax - by) / c = d
1)Multiply by c on both sides to get:
ax - by = cd
2) Add by on both sides to get:
ax = cd + by
3) divide by a on both sides to get:
x = (cd + by) / a
Just for future reference always put ^ for exponents. The answer is y-6 though.
(y-4)(y-6) create that trinomial. You can prove that by using the FOIL algorithm
Answer:
The 90% confidence interval for the population mean iron concentration is between 0.167 cc/m³ and 0.195 cc/m³.
Step-by-step explanation:
We have that to find our
level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Ztable as such z has a pvalue of
.
So it is z with a pvalue of
, so 
Now, find M as such

In which
is the standard deviation of the population and n is the size of the sample.

The lower end of the interval is the sample mean subtracted by M. So it is 0.181 - 0.0140 = 0.167 cc/m³.
The upper end of the interval is the sample mean added to M. So it is 0.181 + 0.0140 = 0.195 cc/m³.
The 90% confidence interval for the population mean iron concentration is between 0.167 cc/m³ and 0.195 cc/m³.