A normal population has mean =μ7 and standard deviation =σ5. (a) What proportion of the population is less than 18?

P(x< 18) = 0.986

Step-by-step explanation:

Step 1: find the z-score using the formula, z = (x - µ)/σ

Where,

x = randomly chosen values = 18

µ = mean = 7

σ = standard deviation = 5

Proportion of the population that is less than 18 = P(x < 18)

Plug in the values into z = (x - µ)/σ, to get z-score.

z = (18 - 7)/5

z = 11/5 = 2.2

Step 2: Find P(x< 18) = P (z<2.2) using z-table.

The probability that corresponds with z-score calculated is 0.986.

Therefore,

P(x< 18) = 0.986

the median here is 25. your lowest value is 14 and highest value is 48. to find the third quartile, find the medium number in between 25 and 48 which would be 42 i believe.