The mean and standard deviation of the scores are 75 and 9.5 respectively.
The z-score is a means to find the probability of getting a particular score. This is calculated to be:

where x is the score, μ is the mean, and σ is the standard deviation.
To be a part of the top 2.5 percent, the probability is:

The z-score for this probability, that is, P
Two ways:
1) guess factors(trial and error)
2) use quadratic formula.
If you use this method then a = -3, b = -6 and c = -1
x = -b +/- [sqrt(b^2 -4ac)/2a]
substituting a, b, and c into our equation we get:
x = - (-6)+/- [sqrt ((-6)^2) - 4(-3)(-1))/2 (-3)]
x = + 6 +/- [sqrt (36 -4 (3)/-6)] if I didnt make a mistake in my signs
x = + 6 +/- [sqrt (36 -12)/-6)]
x = 6 +/- [sqrt (24)/-6] but sqrt 6 x sqrt of 4 = sqrt 24 hence
x = 6 +/- [ sqrt 6 x sqrt 4 /-6] that is:
x = 6 +/- [sqrt 6 x 2 /-6 ]
so x = 6 + [sqrt 6 x 2/-6] and x = 6 - [sqrt 6 x 2/-6]
Answer:
32.625
Step-by-step explanation:
a square has all equal side so u divieded the amount of she used by 4
Answer:
14
Step-by-step explanation:
You can solve using PEMDAS:
Parentheses
Exponents
Multiplication
Division
Addition
Subtraction
3(2+5)-5(3)+8=?
3(7)-5(3)+8=?
No exponents
3(7)-5(3)+8=?
21-15+8=?
No division
21-15+8=?
21-7=?
21-7=14
3(2+5)-5(3)+8=14