Answer:
77 nickels
106 dimes
Step-by-step explanation:
Let there be n nickes and d dimes
Since there are 183 coins, we can write:
n + d = 183
Also, the value of nickel is 0.05 and dime is 0.1, total value is 14.45, so we can write:
0.05n + 0.1d = 14.45
Solving 1st equation for n, we have:
n = 183 - d
Putting this into 2nd equation and solving for d:
There are 106 dimes
Since, n = 183 - d
n = 183 - 106
n = 77
There are 77 nickels
Answer:
Number of families that should be surveyed if one wants to be 90% sure of being able to estimate the true mean PSLT within 0.5 is at least 43.
Step-by-step explanation:
We are given that one wants to estimate the mean PSLT for the population of all families in New York City with gross incomes in the range $35.000 to $40.000.
If sigma equals 2.0, we have to find that how many families should be surveyed if one wants to be 90% sure of being able to estimate the true mean PSLT within 0.5.
Here, we will use the concept of Margin of error as the statement "true mean PSLT within 0.5" represents the margin of error we want.
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<u>SO, Margin of error formula is given by;</u>
Margin of error =
where, = significance level = 10%
= standard deviation = 2.0
n = number of families
Now, in the z table the critical value of x at 5% ( ) level of significance is 1.645.
SO, Margin of error =
0.5 =
n =
= 43.3 ≈ 43
Therefore, number of families that should be surveyed if one wants to be 90% sure of being able to estimate the true mean PSLT within 0.5 is at least 43.