My thread of questions

[ngRISING]

integrate
x/2√x . = ( x ) ( 2 x ^ -1/2 )
              = [( x^2 )/2] x[( 2 x ^1/2 )/ .5]
              =

a bit rusty. this question is taken from essetials 16C

[d0minicz]

If its
=
=
=

[ngRISING]

why did x^1/2 move to the top. i know x^1/2 = squareroot x.

[Damo17]

why did x^1/2 move to the top. i know x^1/2 = squareroot x.

[khalil]

Say that the probability of something being accepted it 0.86 and prob of  another thing being accepted is 0.77. They are not dependent.

To find the probability that they are both rejected, do we do this
(1-0.86)*(1-0.77) or this 1-(0.86*0.77)?  The latter is correct, but why not the former?

[Flaming_Arrow]

Say that the probability of something being accepted it 0.86 and prob of  another thing being accepted is 0.77. They are not dependent.

To find the probability that they are both rejected, do we do this
(1-0.86)*(1-0.77) or this 1-(0.86*0.77)?  The latter is correct, but why not the former?

(1-0.86)*(1-0.77)

[khalil]

Say that the probability of something being accepted it 0.86 and prob of  another thing being accepted is 0.77. They are not dependent.

To find the probability that they are both rejected, do we do this
(1-0.86)*(1-0.77) or this 1-(0.86*0.77)?  The latter is correct, but why not the former?

(1-0.86)*(1-0.77)

??

[/0]

Flaming Arrow is right

0.86*0.77 is the probability that both are accepted, so 1-(0.86*0.77) is the probability that NOT both of them are accepted, i.e. AT LEAST one is rejected.

(1-0.86)(1-0.77) is the probability that both are rejected.

[shinny]

Say that the probability of something being accepted it 0.86 and prob of  another thing being accepted is 0.77. They are not dependent.

To find the probability that they are both rejected, do we do this
(1-0.86)*(1-0.77) or this 1-(0.86*0.77)?  The latter is correct, but why not the former?

The first one represents the probability that both are rejected while the second represents the probability that not both are accepted. The difference is, the second one includes the cases where one is accepted, and the other not, whereas the first is specifically finding the probability of both being rejected.

EDIT: /0 beat me to it ]:

[khalil]

The length of an engine part must be between 4.81 and 5.20 cm. In mass production it is found that 0.8% are too short and 3% too long. Assume it is normally distributed!

Each part costs $4 to produce; those that turn out too long are shortened at an extra cost of $2 and those that turn out to be too short have to be rejected. Find the exprected total cost of producing 100 parts that meet the requirements.

I did this: 96.2*4+0.03*4+0.008*6= 401.6....but the answers say 409.28

[kamil9876]

you worked out something different. I think you tried to work out the expected cost if we pick 100 parts and do whatever it is we are supposed to do with them.

The question is different, it wants how much you have to pay to be expected 100 GOOD parts. Let's say we need X parts in order to be expected to get 100 GOOD parts. Out of those X parts we expect of them to be NOT too short and hence have the potential to be GOOD parts. Setting #goodparts=100 we get:



Hence we will pay 4X for the production and 2*0.03X for the shortening since 3% of them are too long.

That means altogether we pay"

4X+0.06X=4.06X=409.27$

[khalil]

I never thought of it that way, thanks again Kamil

[khalil]

How do you get this from this:  ?

[Mao]

It's something I picked up in specialist to rationalize surds:

[khalil]

Thank you