Answer:
It is (2,4) Plz mark brainliest
Step-by-step explanation:
Answer:
Mean = 78.2
Standard deviation = 5.8
Step-by-step explanation:
Mathematically z-score;
= (x-mean)/SD
From the question;
12% of test scores were above 85
Thus;
P( x > 85) = 12%
P(x > 85) = 0.12
Now let’s get the z-score that has a probability of 0.12
This can be obtained from the standard normal distribution table and it is = 1.175
Thus;
1.175 = (85 - mean)/SD
let’s call the mean a and the SD b
1.175 = (85-a)/b
1.175b = 85 - a
a = 85 - 1.175b ••••••••(i)
Secondly 8% of scores were below 70
Let’s find the z-score corresponding to this proportion;
We use the standard normal distribution table as usual;
P( x < 70) = 0.08
z-score = -1.405
Thus;
-1.405 =( 70-a)/b
-1.405b = 70-a
a = 70 + 1.405b ••••••(ii)
Equate the two a
70 + 1.405b = 85 - 1.175b
85 -70 = 1.405b + 1.175b
15 = 2.58b
b = 15/2.58
b = 5.81
a = 70 + 1.405b
a = 70 + 1.405(5.81)
a = 78.16
So mean = 78.2 and Standard deviation is 5.8
Answer:
r = -39
Step-by-step explanation:
So we are trying to solve the equation for r.
-6(2r + 8) = -10(r - 3)
Divide both sides by -2. (This will make distributing much easier.)
3(2r + 8) = 5(r - 3)
Distribute the 3 on the left side and the 5 on the right side,
6r + 24 = 5r - 15
Subtract 24 from both sides.
6r = 5r - 39
Subtract 5r from both sides.
r = -39
So now we have solve the equation.
I hope you find my answer and explanation to be helpful. Happy studying. :)
Y=<span>5 is your answer. Hope this helps :)</span>
