McGraw Hill Glencoe Algebra 2, 2012
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McGraw Hill Glencoe Algebra 2, 2012 View details
6. The Binomial Theorem
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Exercise 33 Page 702

Practice makes perfect
a When looking at making 9 out of 10 attempts, we need to look at the binomial expansion term where exponent for the number of successes, p, is 9.

∑_(k=0)^(10)10!/k!(10-k)!p^(10-k)q^kIn this case, 10-k should equal 9, so k=1. Let's substitute that and simplify.

10!/k!(10-k)!p^(10-k)q^k
10!/1!(10- 1)!p^(10- 1)q^1
â–¼
Simplify
10!/1!* 9!p^9q^1

Write as a product

10*9!/1* 9!p^9q^1
10/1p^9q^1
10p^9q^1

Simplify power

10p^9q

Now, we can substitute the respective probabilities for p and q. Since the place kicker makes 70 % of his kicks, we can say p=0.7 and q=1-0.7 or 0.3.

10p^9q
10( 0.7)^9( 0.3)
â–¼
Evaluate
10(0.04035)(0.3)
0.121

The likelihood that this place-kicker will make 9 of his next 10 attempts is 0.121 or 12.1 %.

b We can complete this part in a similar manner to Part A, except we need the exponent on p to be 8. Since 10- 2=8, we can let k= 2.

10!/k!(10-k)!p^(10-k)q^k
10!/2!(10- 2)!p^(10- 2)q^2
â–¼
Simplify
10!/2!*8!p^8q^2

Write as a product

10*9*8!/2* 1 * 8!p^8q^2
10*9/2*1p^8q^2
90/2p^8q^2
45p^8q^2

Now, we can substitute the respective probabilities for p and q. Since the quarterback completes 60 % of his kicks, we can say p= 0.6 and q=1-0.6 or 0.4.

45p^8q^2
10( 0.6)^8( 0.4)^2
45(0.17)(0.16)
0.12093235

The likelihood that this quarterback will complete 8 of his next 10 passes is about 0.121 or 12.1 %.

c Like in Parts A and B we need to work out the probability of success. In this part, however, we are looking at 5 attempts instead of 10. Let's change the upper bound on the summation accordingly.

∑_(k=0)^55!/k!(5-k)!p^(5-k)q^kTo be successful 2 out of 5 times, the exponent on p needs to be 2. Therefore, 5-k=2 when k=3. Let's substitute and simplify.

5!/k!(5-k)!p^(5-k)q^k
5!/3!(5- 3)!p^(5- 3)q^3
â–¼
Simplify
5!/3!*2!p^2q^3

Write as a product

5*4*3!/3!* 2*1p^2q^3
5*4/2*1p^2q^3
20/2p^2q^3
10p^2q^3

Since the probability of conversion is 30 %, we can say p= 0.3 and q=1-0.3 or 0.7.

10p^2q^3
10( 0.3)^2( 0.7)^3
10(0.09)(0.343)
0.3087

Therefore, the likelihood of the team making 2 of their next 5 conversion attempts is about 30.9 %.