You need to understand that you're solving for the average, which you already know: 90. Since you know the values of the first three exams, and you know what your final value needs to be, just set up the problem like you would any time you're averaging something.
Solving for the average is simple:
Add up all of the exam scores and divide that number by the number of exams you took.
(87 + 88 + 92) / 3 = your average if you didn't count that fourth exam.
Since you know you have that fourth exam, just substitute it into the total value as an unknown, X:
(87 + 88 + 92 + X) / 4 = 90
Now you need to solve for X, the unknown:
87
+
88
+
92
+
X
4
(4) = 90 (4)
Multiplying for four on each side cancels out the fraction.
So now you have:
87 + 88 + 92 + X = 360
This can be simplified as:
267 + X = 360
Negating the 267 on each side will isolate the X value, and give you your final answer:
X = 93
Now that you have an answer, ask yourself, "does it make sense?"
I say that it does, because there were two tests that were below average, and one that was just slightly above average. So, it makes sense that you'd want to have a higher-ish test score on the fourth exam.
<span>T
Width is 8 and the length is 48! Then add all sides, 8+8+48+48=112.<span>
</span></span>
Answer:
25%
Step-by-step explanation:
The question is:
6 is what percent of 24?
Set up the problem:
6 x
---- = -----
24 100
600 / 24 = 25%
Check your answer:
25% + 25% + 25% + 25% = 100%
6 + 6 + 6 + 6 = 24
Answer:
The number of people needed is 
Step-by-step explanation:
From the question we are told that
The population proportion is 
The margin of error is 
From the question we are told the confidence level is 90% , hence the level of significance is
=> 
Generally from the normal distribution table the critical value of 
is
Generally the sample size is mathematically represented as
![n =[ \frac{Z_{\frac{\alpha }{2} }}{E} ]^2 * p(1-p)](https://tex.z-dn.net/?f=n%20%3D%5B%20%5Cfrac%7BZ_%7B%5Cfrac%7B%5Calpha%20%7D%7B2%7D%20%7D%7D%7BE%7D%20%5D%5E2%20%2A%20p%281-p%29)
=> ![n =[ \frac{1.645 }{0.03} ]^2 * 0.65(1-0.65)](https://tex.z-dn.net/?f=n%20%3D%5B%20%5Cfrac%7B1.645%20%7D%7B0.03%7D%20%5D%5E2%20%2A%200.65%281-0.65%29)
=>
The decimal of 2.1 is greater than 2.0 but less than 2.42
