Roger is standing next to a tree where his shadow is 3 feet long and the shadow of the tree is 18 feet long.
1 answer:
You might be interested in
Answer:
The expression that can be used is 0.80x
Step-by-step explanation:
Let
x ----> original price of an item
Remember that
That means---> the sale price is 80% of the original price
To find out the sale price, determine the 80% of the original price
----> percentage in decimal form
Multiply the original price by the percentage in decimal form to obtain the sale price
so
Answer:
a) E(X) = 71
b) V(X) = 20.59
Sigma = 4.538
Step-by-step explanation:
<em>The question is incomplete:</em>
<em>According to a 2010 study conducted by the Toronto-based social media analytics firm Sysomos, 71% of all tweets get no reaction. That is, these are tweets that are not replied to or retweeted (Sysomos website, January 5, 2015). </em>
<em> Suppose we randomly select 100 tweets. </em>
<em>a) What is the expected number of these tweets with no reaction? </em>
<em>b) What are the variance and standard deviation for the number of these tweets with no reaction?</em>
This can be modeled with the binomial distribution, with sample size n=100 and p=0.71, as the probability of no reaction for each individual tweet.
The expected number of these tweets with no reaction can be calcualted as the mean of the binomial random variable with these parameters:
The variance for the number of these tweets with no reaction can be calculated as the variance of the binomial distribution:
Then, the standard deviation becomes: