Answer:
About <em>4 hours.</em>
Step-by-step explanation:
To find the answer we will <em>add both percentages</em> of <u><em>Watching TV</em></u> and <u><em>Homework</em></u>. 8% + 13% = <em>21%</em>. Now we will <em>divide 100 by 21</em> and we get<em> 4 hours a day.</em>
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:
a)59.125, b)67.5, c)None
Step-by-step explanation:
Mean = All values added up and divided by the number of values
Median = Put all numbers in order from least to most and use the middle one, if there are two, use the mean of those two
. The middle ones are 60 & 75 so 
Mode = The number that repeats more times. In this case none of them repeat.
