Question

Score: 0.6 of 1 pt 3 of 9 (9 complete) 6.2.5 Given a normal distribution with p = 100 and a = 10, complete parts (a) through (d). Click here to view page 1 of the cumulative standardized normal distribution table, Click here to view page 2 of the cumulative standardized normal distribution table. (Round to four decimal places as needed) b. What is the probability that X<75? The probability that X < 75 is 0.0062 (Round to four decimal places as needed.) c. What is the probability that X < 90 or X> 115? The probability that X < 90 or X>115 is 0.2255 (Round to four decimal places as needed) d. 90% of the values are between what two X-values (symmetrically distributed around the mean)? 90% of the values are greater than and less than (Round to two decimal places as needed) Enter your answer in the edit fields and then click Check Answer All parts showing Clear All TO SOTT
whats d

Answer 1

H = 100,0 = 10 d.) P(X1<x< X2) = 0.90 T- X1 100 => PG 10 X2 – 100 10 = 0.90 0 => P(Z1 <2<Z2) = 0.90 as we know standard normal curve is symmetrical about mean or Z = 0 => 1-2P(Z <21) = 0.90 => P(Z < Z1) = 0.05 (use 2 table or excel function : NORM SINV (0.05)) => 21 = 1.64 X1 - 1 = => 1.64 - X1 - 100 10 => X1= 100+ 16.40 => X1= 116.40 Difference from mean = 116.40 - 100 = 16.40 Now Value below the mean = 100 - 16.40 = 83.60

Ans:90% of the values are greater than 83.60 and less than 116.40