What we know:
shape is circular
Area=64π yr²
Area=πr²
circumference=2πr
In order to find circumference we need r=radius. We can use the area to find r by solving for r using substitution of the information we know above.
Area=πr²
64π=πr² substitution
64π/π=π/πr² multiplicative inverse
64=r²
√64=√r² properties of radicals
8=r We would get two solutions, a positive and negative one but we will only use the positive solution since radius is positive
Circumference=2πr
C=2π(8)=16π yards
19 is a prime number so 1, 19
hope this helps!
Let 
be the random variable for the number of marks a given student receives on the exam.
10% of students obtain more than 75 marks, so
where 
follows a standard normal distribution. The critical value for an upper-tail probability of 10% is
where 
denotes the CDF of , and 
denotes the inverse CDF. We have
Similarly, because 20% of students obtain less than 40 marks, we have
so that
Then 
are such that
and we find
I think 2 equal ratios are called a <u>proportion</u>
