A teacher would like to estimate the mean number of steps students take during the school day. To do so, she selects a random sa
mple of 50 students and gives each one a pedometer at the beginning of the school day. They wear the pedometers all day and then return them to her at the end of the school day. From this, she computes the 98% confidence interval for the true mean number of steps students take during the school day to be 8,500 to 10,200. If the teacher had used a 90% confidence interval rather than a 98% confidence interval, what would happen to the width of the interval
The answer is "It would decrease, but not necessarily by 8%".
Step-by-step explanation:
They know that width of the confidence level is proportional to a confidence level. As just a result, reducing the confidence level decreases the width of a normal distribution, but not with the amount of variance in the confidence level. As just a result, when a person teaches a 90% standard deviation rather than a 98 percent normal distribution, the width of the duration narrows.
First, you convert 5% to decimal. For your info, percents are always equal to 100. So, you divide 5 by a 100, which gives you 0.05. Then, you multiply 2.95 by 0.05. 2.95 x 0.05 is 0.1475 which is about 0.15. Then, you add 0.15 to 2.95. The total cost of a $2.95 notebook plus 5% is about $3.10.
To solve a system of equations, we can add the two equations and solve for one of the remaining variables -- let's try to eliminate the variable when we add the two equations together.
Right now, there's a term in the first equation, and a term in the second equation, so if we add those together, we'll be able to eliminate the variable altogether and solve for .
However, when we also have a term in the first equation and term in the second equation, so adding these together will also eliminate the term, leaving a on the left-hand side of the equation.
If we add the two numbers on the right side of the equation, we get , which does not equal , meaning there are no solutions to this system of equations.