If X is normal distribution random variable with mean $μ= 10$ and standard deviation $σ= 2$, Z is standard normal variable and F(Z) is cumulative distribution function, then which of the following are true? [Given that $F(1.5) = 0.9332, F(3) = 0.9986, F(2.25) = 0.9878$ and $F(1) = 0.8413$] (A) $P(X < 13) = 0.9332$ Choose the correct answer from the options given below: |
(A) and (D) only (A), (B) and (C) only (B), (C) and (D) only (A), (C) and (D) only |
(A), (C) and (D) only |
The correct answer is Option (4) → (A), (C) and (D) only Given $X$ is normal with $\mu=10,\;\sigma=2$ Standardization formula $Z=\frac{X-\mu}{\sigma}=\frac{X-10}{2}$ (A) $P(X<13)$ $Z=\frac{13-10}{2}=1.5$ $P(X<13)=F(1.5)=0.9332$ (A) is true (B) $P(X>16)$ $Z=\frac{16-10}{2}=3$ $P(X>16)=1-F(3)=1-0.9986=0.0014$ (B) is false (C) $P(12<X<14.5)$ $Z_1=\frac{12-10}{2}=1$ $Z_2=\frac{14.5-10}{2}=2.25$ $P(12<X<14.5)=F(2.25)-F(1)=0.9878-0.8413=0.1465$ (C) is true (D) $P(X>8)$ $Z=\frac{8-10}{2}=-1$ $P(X>8)=1-F(-1)=F(1)=0.8413$ (D) is true The correct options are (A), (C) and (D). |