[6.18] ([1] 7.52) resistors to be used in a circuit have average resistance 200 ohms and standard deviation 10 ohms. suppose 25 of these resistors are randomly selected to be used in a circuit. a) what is the probability that the average resistance for the 25 resistors is between 199 and 202 ohms? b) find the probability that the total resistance does not exceed 5100 ohms.

a)  0.5328   b) 0.9772

Step-by-step explanation:

Given : Resistors to be used in a circuit have average resistance 200 ohms and standard deviation 10 ohms.

  and  

We assume that the resistance in circuits are normally distributed.

a) Let x denotes the average resistance of the circuit.

Sample size : n= 25

Then, the probability that the average resistance for the 25 resistors is between 199 and 202 ohms :-

b) Total resistors = 25

Let Z be the total resistance of 25 resistors.

To find P(Z≤5100 ohms) , first we find the mean and variance for Z.

Mean= E(Y) = E(25 X)=25 E(X)=25(200)= 5000 ohm

The probability that the total resistance does not exceed 5100 ohms will be :

Hence, the probability that the total resistance does not exceed 5100 ohms = 0.9772

something that characterises a right triangle is the fact that we may use pythagoras' theorem to find any one of its sides given that we have the length of the other two sides. here, we have the length of the hypotenuse, √(87) yd, and one other side, √(23) yd, thus we can easily find the length of the remaining side using pythagoras' theorem as defined below:

c^2 = a^2 + b^2, where c is the length of the hypotenuse, and a and b are the lengths of the other two sides.

thus, given that c = √(87) and a = √(23), we may substitute these into the formula we defined above to get:

c^2 = a^2 + b^2

(√87)^2 = (√23)^2 + b^2 (substitute c = √87 and a = √23 into the equation)

87 = 23 + b^2 (evaluate (√87)^2 = 87 and (√23)^2 = 23 - remember that the square root of a number, squared will equal that very same number)

64 = b^2 (subtract 23 from both sides)

√64 = b (take the square root of both sides)

8 = b (evaluate √64 = 8)

therefor, the length of the unknown leg in the right triangle is 8 yd (first answer).

associative property hopes this ! : )

step-by-step explanation: