Abox in a supply room contains 22 compact fluorescent lightbulbs, of which 8 are rated 13-watt, 9 are rated 18-watt, and 5 are rated 23-watt. suppose that three of these bulbs are randomly selected. (round your answers to three decimal places.)

(a) what is the probability that exactly two of the selected bulbs are rated 23-watt?
(b) what is the probability that all three of the bulbs have the same rating?
(c) what is the probability that one bulb of each type is selected?
(d) if bulbs are selected one by one until a 23-watt bulb is obtained, what is the probability that it is necessary to examine at least 6 bulbs?

a)P(exactly 2 bulb from watt)= 0.11

b)P=0.097

c)P=0.233

d)P=0.235

Explanation:

Total bulb = 22

13 watt bulb = 8

18 watt = 9

23 watt = 5

We have to select 3 bulb out of 22 bulb

We know that probability is the ratio of favor condition to the total condtion.

The total number of way to select 3 bulb out of 22 =N

a)  

P(exactly 2 bulb from watt)= 0.11

b)

The probability that all three of the bulbs have the same rating =P

P=0.097

c)

The probability that one bulb of each type is selected=P

P=0.233

d)

The probability that it is necessary to examine at least 6 bulbs =P

P=0.235

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia

blue light is scattered in different directions by the tiny molecules of air. blue is scattered more than other colours because it has a shorter distance to travel which results in smaller waves. this is why we see a blue sky most of the time.