A research study found that in one physics class, the correlation between pre-exam and post-exam grades was 0.90. The variance of pre-exam grades was 9 and the variance of post-exam grades was 16. Thus, the variance of the difference between pre-exam and post-exam grades is:.

Variance of difference between pre-exam and post-exam grades = 10.8

Step-by-step explanation:

Correlation (X,Y) = Covariance (X,Y) / √ { Variance (X) . Variance (Y) }

Given : Correlation (Pre & post exam grade) = 0.9 ; Variance (Pre exam grade) = 0.90 ; Variance (Post exam grade) = 16

So, 0.9 = Covariance (X,Y) / √ { 16 x 9 }

0.9 = Covariance (X,Y) / 12

Covariance (X,Y) = 12 x 0.9 = 10.8

shift 4 units up, and 1 unit left.

it will translate f(x) = 3^x to g(x) = 3^(x+1) + 4

hello,

b) 62.47% of the students are between 14 and 18 years old.

step-by-step explanation:

mean = 15 and standard deviation = 2

student between 14 to 18

formula used z-score

for age 14 , z score

using z-table , p(z> -0.5)=0.3085

for age 18 , z score

using z-table , p(z< 1.5)=0.9332

p(-0.5< z< 1.5)=0.9332-0.3085 = 0.6247

thus, 62.47% of the students are between 14 and 18 years old.

click to let others know, how is it

0.0

0 votes

1

report

read more on -

step-by-step explanation: