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If the probability that a baby born in a certain hospital will speak in the next day is 1/4, what is the probability that at least 2 babies out of a cluster of 5 babies will speak tomorrow?

 Apr 26, 2018
 #1
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+2

If the probability that a baby born in a certain hospital will speak in the next day is 1/4, what is the probability that at least 2 babies out of a cluster of 5 babies will speak tomorrow?

 

The prob that LESS than 2 will speak is

 5C0 * (0.25)^0 * (0.75)^5 +  5C1 * (0.25)^1 * (0.75)^4

= (0.75)^5 +  5 * 0.25 * (0.75)^4

(0.75)^5+5*0.25*(0.75)^4 = 81/128

 

so the prob that 2 or more will speak is    1- 81/128 = 47/128

 Apr 26, 2018
edited by Melody  Apr 26, 2018
 #2
avatar+290 
+3

wow! thanks melody!

 Apr 26, 2018
 #3
avatar+99394 
+2

You're welcome.  I hope you fully understand :)

Melody  Apr 26, 2018
 #4
avatar+290 
+4

i do, thanks so much to you for helping me!

TheMathCoder  Apr 26, 2018

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