Elena received a $30 gift for her birthday. She plans to use it to buy one or more books. Elena will have to pay 8% sales tax on
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We need to find the base x in the following equation:
First, lets convert 365 from base 7 to base 10. This is given by
where the upperindex denotes the position of eah number. This gives
that is, 365 based 7 is equal to 194 bases 10.
Now, lets do the same for 43 based x. Lets convert 43 based x to base 10:
where again, the superindex 0 and 1 denote the position 0 and 1 in the number 43. This gives
Now, we have all number in base 10. Then, our first equation can be written in base 10 as
For simplicity, we can omit the 10 and get
so, we can solve this equation for x. By combining similar terms. we have
and by moving 197 to the right hand side, we obtain
Finally, we get
Therefore, the solution is x=5
Answer:
Critical value: z = 1.28
The 80% confidence interval for the mean repair cost for the washers is between $46.487 and $82.033.
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 1-0.1 = 0.9, so z = 1.28
Now, find the margin of error M as such
In which is the standard deviation of the population and n is the size of the sample.
So
The lower end of the interval is the mean subtracted by M. So 64.26 - 17.773 = $46.487.
The upper end of the interval is M added to the mean. So 64.26 + 17.773 = $82.033.
The 80% confidence interval for the mean repair cost for the washers is between $46.487 and $82.033.