Question

binomial probabilty
According to the Website Anwers.com, 10-13% of Americans are left-handed. Assume that the percentage is 11%. If we select 9 people at random, find the probability that the number who are left handed is
a, at least 2

Answer 1

at least two means
2, or 3, or 4, or 5, or 6 or 7 or 8 or 9
which is way too many probabilities to compute
can you think of a much faster way?

Answer 2

i was thinking that i can find at most 1 and then subtract my answer from 100% @satellite73

Answer 3

would i be right that way?

Answer 4

not "at most one" but rather "exactly 1" also "exactly 0" find those two, add them up, and subtract the result from one to get the answer to "at least 2"

Answer 5

exactly none is the easiest one
do you know what it is?

Answer 6

noo

Answer 7

ok so we go slow
11% are left handed, what is the percent that is not left handed?

Answer 8

.11

Answer 9

100-11 =89

Answer 10

\(11\%=.11\) yes

Answer 11

and so \(89\%=.89\) for not left handed
the probability that 9 in a row are not left handed is therefore
\[P(x=0)=(.89)^9\] which you will need a calculator to compute

Answer 12

i had the overall sing the binomial formula to be 0.3504

Answer 13

we are not done
we still need
\[P(x=1)\]

Answer 14

i had for the second 0.3897

Answer 15

so far all we have computed is the probability that none are left handed
probability that one is left handed is
\[P(x=1)=9\times (.11)\times (.89)^8\]

Answer 16

for that one i get \(.433\)

Answer 17

for a final answer of
\[1-.433-.3504\]

Answer 18

oh ok..so i need not convert to any percentage right

Answer 19

no you just need to subtract to get the probability
if you want for some reason to convert to a percent, move the decimal over two places

Answer 20

oh ok..

Answer 21

u the best

Answer 22

yw