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Archive for the ‘Probability’ Category

Question: (Math)Statistics help- It’s urgent!10 points for correct answer!?

Tyre pressures on a certain type of car independently follow a normal distribution with mean 1.9 bars and standard deviation 0.15 bars.
1. Find the probability that all four tyres on a car of this type have pressures between 1.82 bars and 1.92 bars.

2. Safety regulations state that the pressures must be between 1.9-b bars and 1.9+b bars. It is known that 80% of tyres are within these safety limits. Find the safety limits.

The answers to these questions are:
1: (0.256)^4
2.limits between 1.71 and 2.09

Could you guys please help me solve this question particularly the second one? Please give me a guidance on how to arrive to the answer. Thank you!
And if you can’t help, please don’t bother answering!

Answer: 1.) z+= (1.92-1.9)/.15=.133 z-=(1.82-1.9)/.15=-.5333

USe your Z-score tables and you will find the areas to be .0517 for .13 and .2019 for .53 added together you have .2536 , they got .256 using a greater accuracy. So the probability that one tire is within these standards is .256. The probability that all 4 are is .256^4.

2.) So the area on the standard z-distribution from the mean to is .40, with .40 coming from the negative side. Using the table this gives a z-score of 1.285 and -1.285 for the negative side.

So the now we know that

z=(mean-value)/standard deviation
so
value=mean-z*standard deviation or 1.9-1.285*.15 = 1.71
and 1.9+1.285*.15 = 2.09

Probability & Statistics Tutor -Sample 3 -Standard Deviation

Question: Help With Math Probability And Other Problems?

Well here are my problems
1. How many wyas can 9 people be seated at a round table
2.From a standard deck of 52 cards, what is the probability that both are aces or both are black
3.50 tickest numbered 1 to 50 are placed in a box. A ticket is drawn and put back into the box. A second ticket is then drawn. What is the probability that they number on both tickets was greater than 35?

Can anyone help me with these?

Answer: (a) 9! (9×8x7×6x5×4x3×2x1)
(b) It’s an “or” case so you have to mutiply. (4C2)/(52C2) x (26C2)/(52C2)
(c) (15C1)/(50C1) x (15C1)/(50C1)

Probability of Independent Events – YourTeacher.com – Math Help

Below are methods of continuous probability distribution. Continuous probability distribution techniques are often used in continuous probability distributions problems and continuous data distribution problems in statistics. The formulas for continuous probability distributions below are very useful for calculating the mean and the variance.

Chi Square distribution

Exponential distribution

Normal distribution

Uniform distribution U (a,b)