a school will choose 1 of 7 applicants to fill a position in the chem dept and 2 of 10 to fill 2 positions in physics dept. if none of the applicants is eligible for a position in both depts, how many different sets of 3 applicants are there to fill the 3 positions
a 42
b 70
c 140
d 165
e 315
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probability prob?
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jcan-gmatter
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Hey d0nw0ng,
The C is an indication that it is a combination type problem of the form:
nCr, where n = total number of choices AND r = number that we want to choose/select
In effect nCr means 7 Choose 1 or 10 Choose 2. Then we use the combination formula to identify the total # of ways that we can choose r from n.
Formula is: -
nCr = n! / (n-r)!r!
The C is an indication that it is a combination type problem of the form:
nCr, where n = total number of choices AND r = number that we want to choose/select
In effect nCr means 7 Choose 1 or 10 Choose 2. Then we use the combination formula to identify the total # of ways that we can choose r from n.
Formula is: -
nCr = n! / (n-r)!r!
