A dept. store recieves shipment of 23 new radios. There are 5 defective in the shipment. If 4 radios are selected for display, what is the probability that 2 of them are defective?
The number of ways to select the two defective is:
5C2 = 5! / (2!3!)
The number of ways to select the two non-defective is:
18C2 = 18! / (2!16!).
The total number of ways to select 4 radios out of 23 is:
23C4 = 23! / (4!19!)
Multiply and divide to get the probability:
= (5C2)(18C2) / (23C4)
= (10)(153) / (8855)
= 306 / 1771 = .17278373800113
The answer is approximately .17278 or 17.3%
Good luck in your studies,
~ Mitch ~
When were radios invented?
Who invented radios?
What are their significance?
Did they help in WW1 and WW2, if so, how?
Please can you try to answer some of these questions,
I can’t find any helpful websites to find these answers.
If you do come across any good websites about radio and why it is significant then can you put it in your ’sources’ box!
Thank-you in advance 
Bea x
The original radio was called the ‘wireless telegraph’ and was used to send messages with dots and dashes, just like Samuel Morse’s device. An Italian named Gueliemo Marconi is/was usually credited with the invention of the radio/wireless telegraph, but he was sued for stealing Nikola Tesla’s work, and had to pay millions of dollars of damages to Tesla.
http://inventors.about.com/od/rstartinventions/a/radio.htm
Later, voice and music was sent over radio, and that was a huge leap in entertainment technology, and, of course, military technology. Radio is the basis of both RADAR and something called the ‘proximity fuse’ which helped win WW II.
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Video from Citizen Radio’s live show at the Upright Citizen’s Brigade Theatre (http://www.ucbtheatre.com/). Guests: Comic Janeane Garofalo, Rolling Stone’s Matt Taibbi, Jeremy Scahill (author of the New York Times bestseller “Blackwater”), and Only Son’s and The Moldy Peaches’s Jack Dishel.
Video by Zach Roberts.
Follow hosts Allison Kilkenny (http://twitter.com/allisonkilkenny) and Jamie Kilstein (http://twitter.com/jamiekilstein) for regular news and future show updates with more awesome guests.
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If a nuclear war destroyed almost all of the big cities in the US, would a person be able to get or send out a message through a radio or a walkie talkie? Or would radio towers have to be rebuilt? If radios didn’t work, how hard would it be to get AM or FM frequencies up again?
Researching for a novel. Thanks!
During an atomic blast, an electromagnetic pulse (EMP) is generated. This EMP destroys electronic circuitry in items such as radios, televisions and computers. It also destroys electric wiring and transmission lines.
Your home will not have normal electricity to operate communication devices. Even though some communication satellites in space will still be functioning, cell phones won’t work because the receiving stations will be out of commission .
If your battery operated radio or walkie-talkie is shielded, say with aluminum foil, it will be just fine and work properly immediately after the pulse. The trouble is, no commercial radio stations will be transmitting. Some governments may have shielded transmitters for emergencies.
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On February 26, 2010, a slow-moving storm is parked over the city and up to 20 inches of snow is expected by Saturday. Schools are closed and subways are running with delays on some lines. In Brooklyn, pedestrians struggle to get through the snow and homeowners shoveled their sidewalks.
Duration : 0:2:27
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Would like to get my son walkie-talkies to use to communicate with his best friend during these winter months. Friends house is about 6 blocks away, over the train tracks, all suburban/residential in between (if that matters).
Does anyone have any experience with 2-way radios being used for this distance in this kind of neighborhood? What brand/model worked? Which one didn’t?
Depending on how old your son is, and if his friends’ parents are willing to spend a little cash, you may want to get them CB radios. You do need to realize that they can talk to almost anyone.
http://www.radioshack.com/family/index.jsp?categoryId=2032070&cp=2032052
You also might want to look in to some high end walkie talkies. These might offer more privacey but they all seem to only come with 1 charger for the pair. You may be able to get adaptors or extra chargers.
http://www.radioshack.com/family/index.jsp?categoryId=2032071&cp=2032052
I saw some people connect iPods to their car radios with this cord thing and I’ve never seen that anywhere. Where can I get that?
There are a few ways to get your iPod connected to your car stereo. You can use the adapter that allows your iPod to broadcast music through an unused radio channel, if your car stereo has an Aux adapter built in you can plug a cable into your ipod headphone jack into an Aux input in the stereo or you can use the old fashioned cassette adapter.
http://www.wnyc.org/news/articles/150504 As of last month, when New Jersey signed it into law, there are 14 states that allow the use of medical marijuana. Some people think New York could be No. 15, and are watching as a bill winds its way through the state Senate and Assembly. Go to WNYC.org for the full report.
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I Have an iPod Touch and I have downloaded the application A+ Police Radio Free, and it allows me to listen to police radios in different countries like New Zealand and the U.S.A., and also Australia. It let’s me listen in four Australian States, Queensland, South Australia, Western Australia and New South Wales. I don’t want to get caught listening to this if it’s illegal, so could you please help me?
It really depends on your local laws. Some places it is totally legal, others totally illegal, other fine at home, but not in your car or outside your home.
Part two of RFC Radio’s interview with Steve King (IA) @ CPAC
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