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anonymous
 one year ago
The scores received by students completing a geology exam are normally distributed. If the average score is 122 and the standard deviation is 35, what percentage of students scored between 52 and 122?
(A) 34.0%
(B) 37.5%
(C) 42.0%
(D) 47.5%
(E) 48.0%
anonymous
 one year ago
The scores received by students completing a geology exam are normally distributed. If the average score is 122 and the standard deviation is 35, what percentage of students scored between 52 and 122? (A) 34.0% (B) 37.5% (C) 42.0% (D) 47.5% (E) 48.0%

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anonymous
 one year ago
Best ResponseYou've already chosen the best response.0@shinebrightlikeadimon @KyanTheDoodle

Plasmataco
 one year ago
Best ResponseYou've already chosen the best response.0im bad at these, only 13, but I can try.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0any help is better than none

ybarrap
 one year ago
Best ResponseYou've already chosen the best response.2$$ P(52\le X\le 122)\\ =P(52\mu\le X\mu\le 122\mu)\\ =P(\cfrac{52\mu}{\sigma}\le \cfrac{X\mu}{\sigma}\le \cfrac{122\mu}{\sigma})\\ $$ Does this make any sense?

ybarrap
 one year ago
Best ResponseYou've already chosen the best response.2This is converting the probability statement into a zscore, a normal random variable with mean 0 and standard deviation 1. This allows us to use the ztable to figure out the probability.

ybarrap
 one year ago
Best ResponseYou've already chosen the best response.2$$ =P(\cfrac{52\mu}{\sigma}\le \cfrac{X\mu}{\sigma}\le \cfrac{122\mu}{\sigma})\\ =P(2\le \cfrac{X\mu}{\sigma}\le 0)\\ =P(0\ge \cfrac{X\mu}{\sigma}\le 2)\\ $$ The last equation follows from symmetry Do you see what we did here?

ybarrap
 one year ago
Best ResponseYou've already chosen the best response.2This should be sufficient
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