80% of 20 is 80/100 x 20 = 16
So, kelly has used 16 stamps, and has 4 left
The measures of spread include the range, quartiles and the interquartile range, variance and standard deviation. Let's consider each one by one.
<u>Interquartile Range: </u>
Given the Data -> First Quartile = 2, Third Quartile = 5
Interquartile Range = 5 - 2 = 3
<u>Range:</u> 8 - 1 = 7
<u>Variance: </u>
We start by determining the mean,

n = number of numbers in the set
Solving for the sum of squares is a long process, so I will skip over that portion and go right into solving for the variance.

5.3
<u>Standard Deviation</u>
We take the square root of the variance,

2.3
If you are not familiar with variance and standard deviation, just leave it.
This is an awful question. They mean to say the number of hours practicing <em>per week</em> (we'll call it h) varies inversely with the <em>time</em> (t) she runs her event. Unless they mean to imply more practicing makes Tyler slower, in which case she should just get a pizza.
Inverse variation means the product is a constant, we'll call it k.
ht = k
When h = 1 hour t=6 minutes
(1)(6) = k
k = 6 (hour*minutes, but as long as we're consistent we don't need to sweat the unit.)
Decreasing her time by one minute means t = 6 - 1 = 5. We solve for h.
ht = k
h = k/t = 6/5 = 1.2 hours
Answer: 1.2 hours, second choice
Answer: There are 32 students who like brussels sprouts but dislike beans.
Step-by-step explanation:
Since we have given that
Number of students eat in the cafeteria = 120
Fraction dislike lime beans = 
Fraction who dislike lime beans and brussles sprouts both = 
Fraction who dislikes lime beans but not brussles is given by

So, Number of students who like brussels sprouts but dislike lima beans is given by

Hence, there are 32 students who like brussels sprouts but dislike beans.