Answer:
A) 99.7% of people have an IQ between 64 and 136.
B) 5% of people have an IQ score less than 76 or greater than 124.
C) 16% of people have an IQ score greater than 112.
Step-by-step explanation:
The Empirical Rule tells us that, in a normal or 'bell-shaped' distribution, 68% of the data is one standard deviation from the mean, 95% of the data is two standard deviations from the mean, and 99.7% of the data is three standard deviations from the mean.
A) 64 and 136 are 3 standard deviations away from the mean, so 99.7% of people have an IQ between 64 and 136.
B) 76 and 124 are 2 standard devations away from the mean, but the answer is asking what percentage is not between them. 100% - 95% gives us 5%.
C) 112 is one standard deviation away from the mean. If we want to find the percentage greater, then we can do 100% - 50% (as 112 is to the left of the mean), then we can take half of 68 to get 34%, and after subtracting 50% and 34% from the 100%, we get 16%.
(2x + 3y = 12) x (-2)
(4x - 3y = 6) x 1
-4x - 6y = -24
4x - 3y = 6
You can cancel out the x values by adding the two equations together.
(-4x + 4x) + (-6y - 3y) = (-24 + 6)
-9y = -18
y = 2
Solve for x now...
4x - 3(2) = 6
4x - 6 = 6
4x = 12
x = 3
Check... (x = 3, y = 2)
2(3) + 3(2) = 12
6 + 6 = 12
12 = 12 <- this works!
4(3) - 3(2) = 6
12 - 6 = 6
6 = 6 <- this works!
Broken down into steps:
1. Find the slope of the line segment that connecs the points (0,-7) and (4,-15).
2. Start with the point-slope formula for the equation of a straight line:
y-b = m(x-a), where the given point is (a,b). Borrow the value of m that you calculated in (1), above, and insert it into this point-slope formula.
Finish up by subst. the x- and y-values in (-3,6) into this formula.
Done!
You could, of course, solve this result for y if you wished.
Answer:
684
Step-by-step explanation:
Using proportions (equivalent ratios), we can find the number of students that make up the 57% out of the total number of people:
Cross-multiply: 100x = (57)(1200) or 100x = 68,400
Divide: 100x/100 = 68,400/100
Solve for x: x = 684 students
Answer:
16,800 dollars
Step-by-step explanation:
1. find 20 percent of 21,000= 4,200
2. subtract 4,200 from 21,000
21,000
-4,200
16,800 dollars
