cost of pencil = x = 0.07
and cost of eraser = y = 0.03
Step-by-step explanation:
let cost of pencil = x
and cost of eraser = y
So, we have equations:
Solving both equations to find value of x and y
Let:
Multiply eq(1) with 4 and eq(2) with 3 and subtract
Putting value of x in equation 1:
So, x= 0.07 and y = 0.03
cost of pencil = x = 0.07
and cost of eraser = y = 0.03
Keywords: System of equations
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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.
Answer:
<h2>2.2</h2>Step-by-step explanation:
Use the cosine law:
We have:
Substitute:
