School lunch costs $1.25 per day. If there are 21 school days
2 answers:
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Answer:
The 98% confidence interval for the average credit card balance is
(564.04, 635.96).
Step-by-step explanation:
We have to calculate the 98% confidence interval on the average credit card balance.
The sample will consist of the n=30 customers that have credit card.
The sample has a mean of $600 and a standard deviation of $80.
As the population standard deviation is estimated from the sample standard deviation, we will use a t statistic.
The degrees of freedom are:
The critical value for a 98% CI and 29 degrees of freedom is t=2.463 (this can be looked up in a t-table).
Then, the margin of error is:
Then, the upper and lower bounds of the confidence interval are:
Answer: The answer is (b) a ≤ 3 + 2j; j ≥ 14, a ≤ 35.
Step-by-step explanation: Given that Anna is no more than 3 years older than 2 times Jamie’s age. Jamie is at least 14 and Anna is at most 35. We are to select the correct combination of inequalities among the given options.
Also, 'a' and 'j' are the possible ages of Anna and Jamie respectively. Therefore, according to the given information, we can write
Thus, the correct option is (b) a ≤ 3 + 2j; j ≥ 14, a ≤ 35.