In a recent survey, the total sleep time per night among college students was approximately normally distributed with mean μ = 6.78 hours and standard deviation σ = 1.24 hours. you plan to take an srs of size n = 150 and compute the average total sleep time. now you want to use a sample size such that about 95% of the averages fall within ±8 minutes (0.1333 hours) of the true mean μ = 6.78 (a) based on the fact that for n = 150, 2σx = 0.202, should the sample size be larger or smaller than 150? explain. the sample size should be larger than 150, because we are looking for a smaller standard deviation. the sample size should be smaller than 150, because we are looking for a larger standard deviation.

the sample size should be smaller than 150, because we are looking for a smaller standard deviation. correct: your answer is correct.

(b) using the 95 part of the 68−95−99.7 rule, what standard deviation of x do you need such that 95% of all samples will have a mean within 6 minutes of μ? (round your answer to four decimal places.)

0.05 correct: your answer is correct.

(c) using the standard deviation you calculated in part (b), determine the number of students you need to sample. (round your answer up to the nearest student.)

615 incorrect: your answer is incorrect.

students i don't understand how to calculate the population, part c. the others i chose the correct answers.

step-by-step explanation:

1. practice, practice & more practice

2. review errors

3. master the key concepts

do not try to memorise the processes.

4. understand your doubts.

5. create a distraction free study environment

6. create a mathematical dictionary

7. apply maths to real world problems.

step-by-step explanation:

one of the most important purposes of surface treatment is to alter surface properties according to the requirement of specific applications. for example, hydrophobic coating has been utilized on windshield and eyeglasses. gold atom monolayer on substrate has become a popular surface bioconjugation strategy.  

i believe the answer is c.

ratios represent a pattern or relationship that can be scaled.

equivalent ratios are pairs of ratios that represent the same relationship between quantities, and can be generated by multiplying or dividing both quantities in the ratio by the same factor.

in this lesson, students will use double number lines and ratio reasoning to solve ratio problems. by partitioning double number lines into proportionate intervals, students will build an understanding of equivalent ratio relationships as those that are generated by multiplying or dividing two related quantities by the same number. this lesson will build upon students' prior understanding of multiplicative comparisons, number line reasoning and equivalent fractions (while highlighting the difference between equivalent fractions and equivalent ratios); and will build toward future work in this unit on building ratio tables, and work in future grades in proportionality, scaling, and expressing and graphing linear functions.

step-by-step explanation:

ratios represent a pattern or relationship that can be scaled.

equivalent ratios are pairs of ratios that represent the same relationship between quantities, and can be generated by multiplying or dividing both quantities in the ratio by the same factor.

in this lesson, students will use double number lines and ratio reasoning to solve ratio problems. by partitioning double number lines into proportionate intervals, students will build an understanding of equivalent ratio relationships as those that are generated by multiplying or dividing two related quantities by the same number. this lesson will build upon students' prior understanding of multiplicative comparisons, number line reasoning and equivalent fractions (while highlighting the difference between equivalent fractions and equivalent ratios); and will build toward future work in this unit on building ratio tables, and work in future grades in proportionality, scaling, and expressing and graphing linear functions.