81\3 using the distributive property
1 answer:
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Answer:
David find <u>8</u> quarters.
Step-by-step explanation:
Given:
David was in need for some money so he decided to clean out the water fountain at the mall he found 20 nickels and quarters.
The collection of nickels and quarters totaled to 2.6.
Now, to find the quarters David find.
Let the number of nickels be
And the number of quarters be
Thus, the number of nickels and quarters he found:
⇒ .........( 1 )
The totaled of nickels and quarters:
(As 1 nickel=$0.05 and 1 quarter=$0.25)
Now, putting the equation ( 1 ) in the place of we get:
⇒
⇒
<em>Subtracting both sides by 1 we get:</em>
⇒
<em>Dividing both sides by 0.20 we get:</em>
⇒
So, the quarters = 8.
Therefore, David find 8 quarters.
Answer:
A score of 314 is needed to be in the top 25% of students who take this exam.
Step-by-step explanation:
We are given that one of the tests provided by the NAEP assesses the reading skills of twelfth-grade students. In recent years, the national mean score was 289 and the standard deviation was 37.
Let X = <u><em>scores of the tests provided by the NAEP</em></u>
The z-score probability distribution for the normal distribution is given by;
Z = ~ N(0,1)
where, = national mean score = 289
= standard deviation = 37
Now, we have to find how high a score is needed to be in the top 25% of students who take this exam, that means;
P(X > x) = 0.25 {where x is the required score}
P( >
) = 0.25
P(Z > ) = 0.25
In the z table, the critial value of z that represents the top 25% of the area is given as 0.6745, that is;
x = 289 + 24.96 = 313.96 ≈ 314
Hence, a score of 314 is needed to be in the top 25% of students who take this exam.