Question 87985: I need help with these problems:
Problem #1
The blood types B- and AB- are the rarest
of the eight human blood types, representing 1.5% and .6%
of the population, respectively.*
a. If the blood types of a random sample of 1000 blood
donors are recorded, what is the probability that 10 or
more of the samples are AB-?
b. If the blood types of a random sample of 1000 blood
donors are recorded, what is the probability that 20 to 40
inclusive of the samples are B-?
c. If a particular city had a blood drive in which 500 people
gave blood and 3% of the donations were would we
have reason to believe that this town has a higher than
normal number of donors who are B-? (Hint: Calculate
the probability of 15 or more donors being B- for a random
sample of 500 and then discuss the probability
obtained.)
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Problem #1
The blood types B- and AB- are the rarest
of the eight human blood types, representing 1.5% and .6%
of the population, respectively.*
a. If the blood types of a random sample of 1000 blood
donors are recorded, what is the probability that 10 or
more of the samples are AB-?
Using a TI-83 I get;
Answer:1 - binomcdf(1000,0.006,9)= 0.083
----------------------
b. If the blood types of a random sample of 1000 blood
donors are recorded, what is the probability that 20 to 40
inclusive of the samples are B-?
Answer: binomcdf(1000,0,0.015,40)-binomcdf(1000,0.15,19)=0.1231
-----------------------------
c. If a particular city had a blood drive in which 500 people
gave blood and 3% of the donations were ???????, would we
have reason to believe that this town has a higher than
normal number of donors who are B-? (Hint: Calculate
the probability of 15 or more donors being B- for a random
sample of 500 and then discuss the probability
obtained.)
Comment: You left somthing out of your posting; see ???????.
-------
1 - binomcdf(500,0.015,14) = 0.990286
Comment: Prob of >=15 having type B is very high but that is
not an appropriate calculation to answer the question. I better
way would be to test the Hypothesis Ho: p=0.015 using a one-sample
z-Test.
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Cheers,
Stan H.
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