Answer:-4
Step-by-step explanation:
Answer:
a = -2 or a = -5
Step-by-step explanation:
We want 
. We can subtract 2 from both sides of this equation to get 
. We can factor this to get that 
. When the product of two numbers is equal to zero, one of the numbers must be equal to zero. This means that either a + 2 = 0, in which case a = -2, or a + 5 = 0, in which case a = -5.
A touchdown is scored 6 points for each touchdown and the points made after a touchdown is scored 2 points each. We are given the following variables:
t = number of touchdowns
p = number of points after a touchdown
Total score = 6t + 2p
Where 6 times t is the total score given by the number of touchdowns multiplied by 6 points, the same goes for the expression 2p.
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
