Look at the attachment
A box contains 20 lightbulbs, of which 5 are defective. If 4 lightbulbs are picked from the box randomly, the probability that a
1 answer:
Answer:
Option D. 938/969
Step-by-step explanation:
At most 2 defective means 2 or less than 2 bulbs are defective
So, we have 3 cases:
a) No defective bulb. b) 1 defective bulb. c) 2 defective bulbs
Case a) No defective bulb
Total number of bulbs = 20
Number of defective bulbs = 5
Number of non-defective bulbs = 15
Total number of ways to select 0 defective bulb = 15C4 = 1365
Case b) 1 defective bulb
Total number of ways to select 1 defective bulb = 15C3 x 5C1 = 2275
Case c) 2 defective bulbs
Total number of ways to select 2 defective bulbs = 15C2 x 5C2 = 1050
Therefore, total number of ways to select at most 2 defective bulbs = 1365 + 2275 + 1050 = 4690
Total number of ways to select 4 bulbs from 20 = 20C4 = 4845
Therefore, probability of selecting at most 2 defective bulbs =
Therefore, option D gives the correct answer.
You might be interested in
Answer:
The cost for each pound of trail mix is $ 1.75 and each pound of jelly beans is $ 2.75.
Step-by-step explanation:
Let each pound of trail mix cost dollars and each pound of jelly beans cost
dollars.
Given:
7 pounds of trail mix and 9 pounds of jelly beans cost $ 37.
So, --------------- 1
Also, 5 pounds of trail mix and 3 pounds of jelly beans cost $ 17.
So, --------------- 2
Multiplying equation 2 by -3, we get
Now, adding equations 1 and 3, we get
Now, plug in in equation 1 and solve for
.
Therefore, the cost for each pound of trail mix is $ 1.75 and each pound of jelly beans is $ 2.75.