Hello,
So we can first assign HD videos and classic videos to specific variables, x is HD videos and y is classic videos.
Fiona bought 5 HD videos, and 2 classic videos for 31 dollars.
5x + 2y = 31
Iliana bought 3 HD videos and 5 classic videos for 30 dollars.
3x + 5y = 30
Therefore, the final answer is choice D, 5x + 2y = 31 and 3x + 5y = 30.
Answer:
a) 
b) 
c) Mary's score was 241.25.
Step-by-step explanation:
Problems of normally distributed samples can be solved using the z-score formula.
In a set with mean 
and standard deviation 
, the zscore of a measure X is given by:
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this problem, we have that:
a) Find the z-score of John who scored 190
b) Find the z-score of Bill who scored 270
c) If Mary had a score of 1.25, what was Mary’s score?
Mary's score was 241.25.
Answer:n=-1
Step-by-step explanation:n=-6+5
n=-1
Answer:
f
(
x
)
=
−
1
2
x
2
+
3
x
−
1
2
Explanation:
A quadratic function can be written in vertex form as:
f
(
x
)
=
a
(
x
−
h
)
2
+
k
where
(
h
,
k
)
is the vertex and
a
is a constant multiplier.
In our example the vertex
(
h
,
k
)
is
(
3
,
4
)
, so we can write:
f
(
x
)
=
a
(
x
−
3
)
2
+
4
Given that this passes through the point
(
1
,
2
)
, we must have:
2
=
a
(
1
−
3
)
2
+
4
=
4
a
+
4
Subtract
4
from both ends to get:
−
2
=
4
a
Divide both sides by
4
and transpose to find:
a
=
−
1
2
So our quadratic function can be written in vertex form as:
f
(
x
)
=
−
1
2
(
x
−
3
)
2
+
4
We can multiply this out and simplify as follows:
f
(
x
)
=
−
1
2
(
x
−
3
)
2
+
4
f
(
x
)
=
−
1
2
(
x
2
−
6
x
+
9
)
+
4
f
(
x
)
=
−
1
2
x
2
+
3
x
−
9
2
+
4
f
(
x
)
=
−
1
2
x
2
+
3
x
−
1
2
Step-by-step explanation:
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