Jillian said StartRoot 25 EndRoot is irrational because it is a square root. Why is she incorrect? Jillian is incorrect because
2 answers:
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Answer:
The estimate for the number of students who took the test is 23.
Step-by-step explanation:
The Empirical Rule states that, for a normally distributed random variable:
68% of the measures are within 1 standard deviation of the mean.
95% of the measures are within 2 standard deviation of the mean.
99.7% of the measures are within 3 standard deviations of the mean.
In this problem, we have that:
Mean = 78
Standard deviation = 6
Since the normal distribution is symmetric, 50% of the students had scores above the mean and 50% had scores below the mean.
Proportion of students who scored between 72 and 90:
72 = 78 - 6
So 72 is one standard deviation below the mean.
Of the 50% of the students who scored below the mean, 68% scored above 72.
90 = 78 + 2*6
So 90 is two standard deviations above the mean.
Of the 50% of the students who scored above the mean, 95% scored below 72.
Then
0.68*0.5 + 0.95*0.5 = 0.815
81.5% of the students scored between 72 and 90.
Nineteen students had test scores between 72 and 90. Estimate the number of students who took the test.
19 is 91.5% = 0.815 of the total number of students.
How much is 100% = 1?
19 - 0.815
x - 1
Rounding to the nearest whole number
The estimate for the number of students who took the test is 23.
Answer:
7 seconds
Step-by-step explanation:
Distance of the coin above the water is modeled by the equation
where is time taken to cover the distance
Now equating with zero.
So, time taken by the coin to hit the water is 7 seconds.
Answer:
5. 25/36
6. 25/36
7. -3/4 or 6
8. 0 or 4
Step-by-step explanation:
5. Square both sides: x + 4 = 9 - 6 + x
Subtract x from both sides and subtract 9 from both sides:
-5 = -6
Square both sides again: 25 = 36x
Divide both sides by 36: x = 25/36
6. Square both sides: x + 4 = 9 + 6 + x
Subtract x and 9 from both sides: -5 = 6
Square both sides: 25 = 36x
Divide both sides by 36: x = 25/36
7. Square both sides: x + 3 = 5x + 6 - 6 + 9
Add 6 to both sides and isolate it: 6
= 4x + 12
Divide both sides by 2 and then square both sides again:
3 = 2x + 6
9 * (5x + 6) = 4x^2 + 24x + 36
45x + 54 = 4x^2 + 24x + 36
4x^2 - 21x - 18 = 0
Factorize: (4x + 3)(x - 6) = 0 ⇒ x = -3/4 or x = 6
8. Square both sides: 2x + 1 = x^2 - 2x + 1
Move all the terms to one side and combine like terms: x^2 - 4x = 0
Factorize: x(x - 4) = 0 ⇒ x = 0 or x = 4
Hope this helps!