It's the second to last one.
The linear equation:
y = k x + b
We will use first two values and solve the system of equations:
11 = k * 7 + b / *(-1)
13 = k * 8 + b
---------------------
-11 = - k * 7 - b
13 = k * 8 + b
----------------------
2 = k
13 = 16 + b
b = 13 - 16 = -3
y = 2 x - 3 ( y varies directly with x )
Answer:
The proportion of students whose height are lower than Darnell's height is 71.57%
Step-by-step explanation:
The complete question is:
A set of middle school student heights are normally distributed with a mean of 150 centimeters and a standard deviation of 20 centimeters. Darnel is a middle school student with a height of 161.4cm.
What proportion of proportion of students height are lower than Darnell's height.
Answer:
We first calculate the z-score corresponding to Darnell's height using:

We substitute x=161.4 ,
, and
to get:

From the normal distribution table, we read 0.5 under 7.
The corresponding area is 0.7157
Therefore the proportion of students whose height are lower than Darnell's height is 71.57%
<span>x + y = 0 hope this helps </span>