Highland missed 16 out of 78 points on his last test. What letter grade did he earn?
2 answers:
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Solution :
Let x be student will be left handed
P = 0.09
Using the normal approximation to binomial distribution,
a). n = 108,
μ = np = 9.72
= 2.9741
Required probability,
P(x=8) = P(7.5 < x < 8.5)
Using z table,
= P(z<-0.41)-P(z<-0.75)
= 0.3409-0.2266
= 0.1143
b). P(x=12) = P(11.5 < x < 12.5)
Using z table,
= P(z< 0.94)-P(z< 0.60)
= 0.8294 - 0.7257
= 0.1006