What is the ratio 20:17 in its simplest form
2 answers:
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Answer:
A sample size of 79 is needed.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of
, we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of .
For this problem, we have that:
The margin of error is:
95% confidence level
So , z is the value of Z that has a pvalue of
, so
.
What sample size is needed if the research firm's goal is to estimate the current proportion of homes with a stay-at-home parent in which the father is the stay-at-home parent with a margin of error of 0.09?
A sample size of n is needed.
n is found when M = 0.09. So
Rounding up to the nearest whole number.
A sample size of 79 is needed.
Answer:
see below
Step-by-step explanation:
The conversion factor in the box is the product ...
_____
The purpose of a conversion factor is to multiply by 1 in the form of a ratio that changes the units. We know that 1000 Pa = 1 kPa, so the ratio (1 kPa)/(1000 Pa) is the ratio of two equal quantities. It has the value 1 and will change units from Pa to kPa.
Likewise, 100 cm = 1 m, so (1 m)/(100 cm) will change the units from cm to m. However the given expression uses cm³, so we need to multiply by the conversion factor 3 times. That factor is ((1 m)/(100 cm))³ = (1 m³)/(10⁶ cm³).
To choose the appropriate conversion factor, look at the units you have (Pa, cm) and the units you want (kPa, m). Find the relationship these have to each other, and write the ratio so that it will cancel the units you have and leave the units you want.
When SI units are involved the prefixes help you out. k = kilo = 1000; c = centi = 1/100. It is worthwhile to get to know them.