Math Help Forum - View Single Post

jjzshen · #2 April 16th, 2008, 02:57 AM

Quote:

Originally Posted by looi76

Question:
Given that $X \sim N(44,25)$ , find $s$ , $t$ , $u$ , and $v$ correct to 2 decimal places when
$P(X \geq t)=0.7704$

Attempt:
$= P(\frac{X-\mu }{ \sigma } \geq \frac{X-44}{ 5})$

$1 - \frac{X-44}{5} = 0.7704$

This is the problem here. You need to use a normal probability table to find that
$\Pr(Z \geq -0.74) = 0.7704$

Then we have:
$-0.74 = \frac{t-44}{5}\Rightarrow t = 40.3$

The following users thank jjzshen for this useful post:
looi76
$Donate to MHF$