Answer: cost of 1 pot of ivy = $12
Cost of 1 rose bush =$ 10
Step-by-step explanation:
Step 1
Let rose bushes be represented as r
and pot of ivy be represented as p
such that Amy who spent 82 dollars on 7 rose bushes and 1 pot of ivy can be expressed as
7 r + p = 82----- eqn 1
Rob who spent 74 on 5 rose bushes and 2 pots of ivy can be expressed as
5r +2 p = 74----- eqn 2
Step 2
Solving
7 r + p = 82----- eqn 1
5r +2 p = 74----- eqn 2
By elimination method Multiply eqn 1 by 5 and eqn 2 by 7
35r+ 5p= 410--- eqn 3
35r+ 14p =518--- eqn 4
Subtracting eqn 4 from eqn 3
9p = 108
p = 108/9
p=12
p = pot of ivy = $12
therefore rose bush wll be ( from equation 1)
7r+ p= 82
7r=82-12
7r= 70 r= 70/7
r= rose bush =$ 10
The correct option is 20.
The score found for the sample is 20.
<h3>What is Standard error?</h3>
A standard error is a statistic that is applied to test the distribution of data. This metric is comparable to standard deviation. We can calculate the standard error if we know the sample size & standard deviation. It assesses the mean's precision.
Now, according to the question;
Sample mean; 
Sample variance; 
Thus, 
Standard error SE = 1
The amount of scores with in sample must be determined here.
The standard error formula is as follows:

We might rearrange the formula as follows:

Substituting the values;

The sample's number of scores n = 19.98 = 20 (round up)
Therefore, the scores are in the sample is 20.
To know more about the Standard error, here
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8 + 3 (4 - n )
n= 3
8 + 3( 4-3)
8 + 3 * 1
8 + 3 = 11