Recent content by DeShark

It could be used to test a hypothesis. The null hypothesis would be : The probability of failure is < 5%. If you take a sample of 50 parts and get 5 failures, the probability of this is 6.6% so you would not reject the null hypothesis at the 95% confidence level. I.e. 5 defective parts is not...

I should have said: I'm trying to come up with a way to determine if the defect count of a particular widget is 'different' to the usual defect count of a widget.

Sorry for not being clearer: each widget itself is made up of parts, each of which can be 'working' or 'defective'. The exact manner in which the parts are defective is unimportant; just the number of defective parts (or equivalently, the proportion of parts which is defective).

I'm not quite sure what you're trying to achieve here. Do you want to know how many LEDs will be defective on average? Just because you only have two outcomes doesn't mean your probability is 0.5 - every time you cross the road, you can die or live. This doesn't mean you have a 50% chance of...

Hi all. I'm trying to come up with a way to determine if the defectivity of a particular widget is 'different' to the usual defectivity of a widget. The difficulty comes from the fact that widgets are made in batches of 25. We'd like to investigate any widgets which have a higher (or lower)...

Ah... I guess that makes sense if the indices are over different ranges, e.g. j=1,2,3 k=1,2,3,4. It confused me in this case because why would you use two separate indices when one is perfectly adequate. It seems simpler, more obvious and more elegant to just use the one index, given that n=4...

Homework Statement Write out c_{j}x_{j}+c_{k}y_{k} in full, for n=4. Homework Equations The Attempt at a Solution So I figure we have to sum over both j and k. So the answer I obtained is: (c_1x_1+c_1y_1)+(c_1x_1+c_2y_2)+(c_1x_1+c_3y_3)+(c_1x_1+c_4y_4)+...

Refractive index is not only complex, but depends on the frequency of the light for a given material. Generally, though, it's stated for yellow light (more precisely the doublet sodium D-line). The fact that the refractive index depends on the frequency of light accounts for things such as the...

My gut feeling is yes. If you have a photon decomposing into an electron and a positron, then (in the centre of mass frame), the two particles will move apart with the same momentum. If we then measure the position of one of the particles, then we must disturb the momentum of the other -...

Generally, to begin with, the external magnetic field is ignored. You can add a magnetic field which interacts with the magnetic moment of the atom. This gives rise to the Zeeman effect, the splitting of energy levels based on the z-component of the total angular momentum (usually denoted m)...

I think the answer is to do with surface tension playing a greater role than pressure differences. It is after all surface tension that keeps the air molecules together.

The other way to look at it, instead of calculating accelerations and integrating back to get velocity, is to look at the Energy. The change in energy is just mg*(change in height) and this goes into the kinetic energy i.e. 1/2 mv^2.

You might want to consider this as a simple siphon, and given the wording of the question, you should take the first flow rate to be zero. V1 = 0. You know the height between the surface of the water and the exit point, the density of water, atmospheric pressure, etc. The pressure at the exit is...

I don't know where you got the 294N from? 33kg * 9.8 = 323N. g is 9.8, not 8.9! Your maths seems right though. You can check your answer easily also. 230sin(53) + 180sin(37) = 292N, which is close enough (since you rounded your answers) to 294.

Did you get an answer using TSny's advice? I just worked it out using your formula and got a positive answer. What was the negative answer you got and maybe we can work out where you're going wrong? If you got a T2 of 219K, then you need to remember that 0.25 + 0.75 = 1 - i.e. the height...