A study of a population of 1,200 frogs revealed that 12 out of every 180 frogs in the population have spots on their back. Based on the results of this study, how many frogs in the population do NOT have spots on their back?

a.80
b.168
c.1,280
d.1,120

12 answers

prob(spots) = 12/180 = 1/15

so of the 1200 frogs, (1/15)(1200) should have spots, so ..
how many should not have frogs ?

or
prob(not spots) = 14/15
number who don't have spots = (14/15)(1200) = ...

You will of course get the same answer from either method, right ?

YES :) and another way is to say... If 12 out of 180 have spots, then 180-12 do not have spots. So out of 1200, we know the percent with no spots is 168/180 (written as a decimal), then 168/180 times 1200 is also 1120 : )

1,280

then what is the answer because im still confused

1120
Big

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Its 120

Tell me the answer kids :)

My teacher says it’s 80

1,120

It's 1120