Form 5 question about chapter 8 binomial distribution {SPM level}

[Wxlauslen123]

I don't know how to do questions 10 (b). This is a form 5 level question about binomial distribution. The answers are 10.4120 and 3.8397 for 10(b)

 

[Romsek]

[MATH]P[X>\tau] = 1 - \Phi\left(\dfrac{X-\mu}{\sigma}\right)[/MATH]
They give you a couple values of \(\displaystyle \tau\), you've got the table of \(\displaystyle \Phi(x)\)

Plug and Chug

 

[Wxlauslen123]

[MATH]P[X>\tau] = 1 - \Phi\left(\dfrac{X-\mu}{\sigma}\right)[/MATH]
They give you a couple values of \(\displaystyle \tau\), you've got the table of \(\displaystyle \Phi(x)\)

Plug and Chug

Can I know the symbol outside the bracket () means?

 

[Romsek]

Can I know the symbol outside the bracket () means?

It's the CDF of the standard normal distribution. What you've got in the table someone hopefully referenced during lecture or in notes.

 

[Steven G]

There are two unknowns and you can get two equations.


1) Find the Z score to .7, call this number k (since I do not know what it is but you will). k = (8.4-mu)/sd
2) Find the Z score to .25, call this number r (since I do not know what it is but you will). r = (13.2-mu)/sd

Solve the two equations for mu and sd.

 

[Wxlauslen123]

There are two unknowns and you can get two equations.


1) Find the Z score to .7, call this number k (since I do not know what it is but you will). k = (8.4-mu)/sd
2) Find the Z score to .25, call this number r (since I do not know what it is but you will). r = (13.2-mu)/sd

Solve the two equations for mu and sd.

There's not z score for 0.7, the highest is 0.5, mine is following standard normal distribution table

 

[Steven G]

If p(x>8.4) =.7, then p(x<8.4) = ???

You have to think hard and always know that the total area is 1.

 

[Wxlauslen123]

If p(x>8.4) =.7, then p(x<8.4) = ???

You have to think hard and always know that the total area is 1.

0.3?

 

[Steven G]

0.3?

Yes.