As this follows Normal Distribution, we use the formula
mentioned. The p value and the z score from the p value is obtained
from STATKEY (image attached for reference).
الب N = 600 Mean Cu) = 0.70 S.D CO-)= 15 Normal Distribution, As this follows a Z-score X-M olun la X=0.80 Z-score =0.80 -0.70 0.163 = 15/, боо b . People who failed - are the ones who scores less than 49.10. PCX < 0.49) = P(Z < 0.49-0.70 15/5500 prz<-0.343) Source - STATKEY P(Z <-0.343) = 0.366 (imape attacked) ] so, percentage of students who failed the exam the exam is 36.6% © No No. of students who 36.6% of 600 of failed the exam 36.6 100 Х 600 = 219.6 220 Capproximately) Sog ro, 220 students failed the exam .
d.) P-value 0.99 Z Z-sure from the p-value 2.327 [ Source - STATKEY limage attacked) Z= x - u s 2.327 = * -0.7 15 'shoco 1600 xب or X = 2.125 212.5.1 This is impossible to obtain as the greiding monks 100% his friend got 212.50%. and are only from 0% to le the Z-score (is Negative Z-sce indicates the stucent got less than 0.70% [Because for the mean, is exactly 0] to his classmates, he is one among (i) compared the people who sured in the lower half the class, ie, of to 50% of his classmates of
Statkey Theoretical Distribution Normal Distribution- Reset Plot Normal Distribution Left Tail Two-Tail Right Tail Mean Standard Deviation 0.40 0 1 0.35 Edit Parameters 0.30 0.25 0.20 0.366 0.15 0.10 0.05 0.00 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 -0.343 Activate Windows
Statkey Theoretical Distribution Normal Distribution Reset Plot Normal Distribution Left Tail Two-Tail Right Tail Mean Standard Deviation 0.40 0 0.35 Edit Parameters 0.30 0.25 0.20 0.990 0.15 0.10 0.05 0.00 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 2.327 Activate Windows