4. 15 tens, 1 hundred, 5 tens
150
5. 18 tens, 1 hundred, 8 tens
180
note: I hope this helps. I haven't done this in a long time. Sorry X(
Answer:
Se=1.2
Step-by-step explanation:
The standard error is the standard deviation of a sample population. "It measures the accuracy with which a sample represents a population".
The central limit theorem (CLT) states "that the distribution of sample means approximates a normal distribution, as the sample size becomes larger, assuming that all samples are identical in size, and regardless of the population distribution shape"
The sample mean is defined as:

And the distribution for the sample mean is given by:

Let X denotes the random variable that measures the particular characteristic of interest. Let, X1, X2, …, Xn be the values of the random variable for the n units of the sample.
As the sample size is large,(>30) it can be assumed that the distribution is normal. The standard error of the sample mean X bar is given by:

If we replace the values given we have:

So then the distribution for the sample mean
is:

Answer: There are 6 pieces of cloth are rectangles and 9 pieces of cloth are triangles.
Explanation:
Since we have given that
For every 5 pieces of cloth, 2 are rectangles
So, remaining piece will be of triangle so,

3 are triangles.
Ratio of rectangles to triangles is 2:3.
Now, she needs 15 pieces of cloth to complete her scarf,
So, Number of rectangles is needed is given by

Number of triangles is needed is given by

Hence, there are 6 pieces of cloth are rectangles and 9 pieces of cloth are triangles.
Answer:
a) The number of students who enjoy reading only.