Answer:
Without any studying, the score would be about 328
Step-by-step explanation:
The y-intercept of an equation represents the point where its graph crosses the y-axis. At this point the value of x is always equal to 0.
The y-intercept of the equation in this context would represent the Math SAT score of a student who did not do any studying, that is the number of hours spent studying, x = 0.
Substitute x = 0 in the given equation and solve for y;
y = 24.387(0) + 328.182
y = 328.182
Therefore, Without any studying, the score would be about 328
The answer is <span>b.12
</span>
According to the Pythagorean theorem the square of the hypotenuse (c) is the sum of the squares of the legs (a and b):
c² = a² + b²
We have:
a = 3x
b = 15
c = 3x + 3
Now, let's replace these parameters:
c² = a² + b²
(3x + 3)² = (3x)² + 15²
(3x)² + 2 * 3x * 3 + 3² = 9x² + 225
9x² + 18x + 9 = 9x² + 225
Rearrange:
9x² - 9x² + 18x = 225 - 9
18x = 216
x = 216 / 18 = 12
Answer:
(C). 
yd.
Step-by-step explanation:
Population = 135 students
Mean score = 72.3
Standard deviation of the scores = 6.5
Part (a): Students from 2SD and 3SD above the mean
2SD below and above the mean includes 95% of the population while 3SD includes 99.7% of the population.
95% of population = 0.95*135 ≈ 129 students
99.7% of population = 0.997*135 ≈ 135 students
Therefore, number of students from 2SD to 3SD above and below the bean = 135 - 129 = 6 students.
In this regard, Students between 2SD and 3SD above the mean = 6/2 = 3 students
Part (b): Students who scored between 65.8 and 72.3
The first step is to calculate Z values
That is,
Z = (mean-X)/SD
Z at 65.8 = (72.3-65.8)/6.5 = 1
Z at 72.3 = (72.3-72.3)/6.5 = 0
Second step is to find the percentages at the Z values from Z table.
That is,
Percentage of population at Z(65.8) = 0.8413 = 84.13%
Percentage of population at (Z(72.3) = 0.5 = 50%
Third step is to calculate number of students at each percentage.
That is,
At 84.13%, number of students = 0.8413*135 ≈ 114
At 50%, number of students = 0.5*135 ≈ 68
Therefore, students who scored between 65.8 and 72.3 = 114-68 = 46 students
