Question
I need help with question 4.
3. A box contains 15 resistors. Ten of them are labeled 50 and the other five are labeled 100 a. What is the probability that the first resistor is 100 ? b. What is the probability that the second resistor is 100 , given that the first resistor is 50 ? c. What is the probability that the second resistor is 100 , given that the first resistor is 100 ? 4. Refer to Exercise 3. Resistors are randomly selected from the box, one by one, until a 100 resistor is selected. a. What is the probability that the first two resistors are both 50 ? b. What is the probability that a total of two resistors are selected from the box? c. What is the probability that more than three resis- tors are selected from the box?
Explanation / Answer
A) P(first two are both 50 ohm resistors) = (10/15)x(9/14) = 3/7 = 0.4286
B) P(total two resistors are selected) = P(first one is 50 ohm and second one is 100 ohm) = (10/15)x(5/14) = 5/21 = 0.2381
C) P(more than 3 resistors are selected) = P(first 3 resistors are 50ohm)
= (10/15)x(9/14)x(8/13) = 0.2637