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Lefties A total of 11%of students at a large high school are left-handed. A statistics teacher selects a random sample of 100 students and records L= the number of left-handed students in the sample.

a. Explain why L can be modeled by a binomial distribution even though the sample was selected without replacement.

b. Use a binomial distribution to estimate the probability that 15 or more students in the sample are left-handed.

Short Answer

Expert verified

(a)A binomial distribution can be used to model L.L~Bin(100,0.11)

(b) The probability of greater than or equal to 15 left-handed students in the sample is 0.13305.

Step by step solution

01

Part (a) Step 1: Given Information

The number of left-handed pupils in the sample is denoted by the letter L.

The sample size is 100.

In a large school, the percentage of left-handed kids is equal to 11.

02

Part (a) Step 2: Simplification

The following concept was used:

10%condition

n<0.10N

According to the rule, if the sample represents less than 10% of the population, it is safe to assume that the trials are independent and may be modelled using the binomial distribution, regardless of the without replacement sample.

The sample size=100is less than ten percent of a large school's students.

Furthermore, the left-handedness of one student has no bearing on the left-handedness of another, therefore each student's trial is independent.

Since, L~Bin(100,0.11)

As a result, a binomial distribution can be used to model L.

03

Part (b) Step 1: Given information

The number of left-handed pupils in the sample is denoted by the letter L.

The sample size is 100.

In a large school, the percentage of left-handed kids is equal to 11.

04

Part (b) Step 2: Simplification

Consider,

P(L15)=1-P(L<15)P(L15)=1-P(L14)

Using TI- 83 plus

a) Now Press on 2ndand then click on Dist.

b) Go to binomcdf with key.

c) Hit Enter

d) Type 100,0.11,14)

e) Hit Enter

The probability comes to be 0.86695.

P(L15)=1-0.86695P(L15)=0.13305

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