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
.1 repeating - decimal
11% - percentage
Answer: 621
Step-by-step explanation: 28^2+ 13 − 176
length, width, and height.
Answer:
15 hours.
Step-by-step explanation:
We first need to see how much money Rose would earn if she sold the 10 pendents, so we will multiply 4×10.
4×10=40
Now we know, she already has 40 dollars of the 160 dollars she needs.
To find out how much she needs left, we will subtract 40 from 160.
160-40=120
She needs a total of 120 more dollars from working.
To find out how many hours she needs to work, we will divide 120 by 8.
120÷8=15.
In conclusion, she needs to work for at least15 hours to receive enough money.Please help me by marking this brainliest, and giving a thanks!
Answer:
a. -2/12
b. -0.1
c. 1/9
Step-by-step explanation:
-2/12 = -1/6 < -1/8
-0.1 = -1/10 > -1/8
and 1/9 is the only positive fraction, making it simpler to place.
