Answer:
A.
Step-by-step explanation:
when you plot the vertices;
Side AB is perpendicular to side BC
Side AB is parallel to side DC
Side AC is perpendicular to AB
Side AC is perpendicular to DC
Side AC is parallel to side BC
The conclusion made is that ABCD is a rectangle
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
C because 9 x 12 is 108 and so it’s c but I’m sorry if this is wrong
3sinx+1=sinx
2sinx+1=0
2sinx=-1
sinx=-1/2
x=sin^-1 (1/2) = 30 =
/6 (when finding the inverse, always take the positive value, ignore the negative sign)
x is therefore negative in 3rd and 4th quadrant
Therefore values of x are:
180+30=210 = 7
/6
360-3=330 = 11
/6
