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
Responder:
3 horas
Explicação passo a passo:
Dado :
Miguel a cada 45 minutos
Nádia a cada 60 minutos
Número de horas que eles vão se ver no mesmo lugar:
Para fazer isso ;
Obtenha o menor múltiplo comum de 60 e 45
Múltiplos de:
45: 45, 90, 135, 180, 225.
60: 60, 120, 180, 240, 300.
O menor múltiplo comum de 45 e 60 é 180
° Assim, eles se verão no mesmo lugar após 180 minutos;
Número de horas = 180/60 = 3 horas
A: To find the rate in feet per minute, we can use the information given.
Every two minutes, the submarine dives 300 feet. So

.
In order to confirm that our rate is correct, we can use the second set of information given.

=

.
Since we know that the rate is 150 feet per minute, we can multiply it by any number of minutes and get the answer of how deep the submarine is. We can use a variable x to represent the number of minutes and y to represent the depth in feet.

There's our equation.
B: It would be more reasonable to use an equation with the rate feet per minute because it is more accurate since the time interval isn't too big.
Answer: 50.84%
Step-by-step explanation:
(89-59) /59 = 0.5084/100 = 50.84%