Use the normal approximation to the binomial distribution to determine

Nann

Nann

Answered question

2021-09-15

Use the normal approximation to the binomial distribution to determine (to four decimals) the probability of getting 7 heads and 7 tails in 14 flips of a balanced coin. To determine the error of this approximation, also consult the "Statistical Tables" table of binomial probabilities.

Answer & Explanation

davonliefI

davonliefI

Skilled2021-09-16Added 79 answers

Step 1
According to the information given, the event involves 14 balanced coin flips.
(n)=14
As flipping coin has two outcomes as head or tail, probability of getting head or tail is 0.5.
The probability mass function of binomial distribution is,
P(X=x)=nCxpx(1p)nx
With mean =np=7
variance =np(1p)=3.5
For normal approximation XN(np,np(1p))
Step 2
Probability that there are exact 7 heads and 7 heads can be calculated as:
P(X=7)=P(70.5<X<7+0.5)
P(6.5<X<7.5)=P(6.571.8708<Xnpnp(1p)<77.51.8708)
=P(0.2673<Z<0.2673)
=0.2107 (Calculated using standard normal table)
Step 3
The binomial probability using statistical table is 0.209.
Both values using normal approximation and using statistical table are near about same; having slight difference of 0.0017.

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