60% of the students are girls.Boys are 12. how many students are there?

Mathematics

1 answer:

Nonamiya [84]3 years ago

3 0

If 40% are boy and there are 12 boys
40% of girls would be 12 and another 20% is 6 so
You add 12+12+6=30 students total

You might be interested in

Helppppppppppppp pleaseeeeeeeeeeeeeeeee

Mashcka [7]

Answer:

a c e ace ace ace ace ace ace ace

3 0

3 years ago

Suppose a batch of metal shafts produced in a manufacturing company have a standard deviation of 1.4 and a mean diameter of 212

zhannawk [14.2K]

Answer:

$P(211.9$

And using the normal standard table or excel we can find this probability with this difference:

$P(-0.639$

Step-by-step explanation:

For this case we define the random variable X="metal shafts" produced in a manufacturing company, and we have the following properties given:

$E(X)= 212, \sigma = 1.4$

Previous concepts

The central limit theorem states that "if we have a population with mean μ and standard deviation σ and take sufficiently large random samples from the population with replacement, then the distribution of the sample means will be approximately normally distributed. This will hold true regardless of whether the source population is normal or skewed, provided the sample size is sufficiently large".

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".

Solution to the problem

They select a sample if size n=4, by the central limit theorem the distribution for the sample mean is given by:

$\bar X \sim N(\mu=212, \frac{1.4}{\sqrt{80}}= 0.1565)$