The average number of mosquitos in a stagnant pond is 80 per square meter with astandard...

The average number of mosquitos in a stagnant pond is 80 per square meter with astandard deviation of 12. If 36 square meters are chosen at random for a mosquitocount, find the probability that the average of those counts is more than 81.6 mosquitosper square meter. Assume that the variable is normally distributed.

A)0.3%B)21.2%C)78.8%D)28.8%

Solutions

Expert Solution

Solution :

Given that ,

mean = = 80

standard deviation = = 12

= / n = 12 / 36 = 2

P( > 81.6) = 1 - P( < 81.6 )

= 1 - P[( - ) / < (81.6 - 80) /2 ]

= 1 - P(z < 0.8)

= 1 - 0.7881 = 0.2119 = 21.2% , Option B is correct.

orchestra answered 1 year ago

Next > < Previous

Related Solutions

Jerome read that in temperate climes, there are more than 133 spiders per square meter of...

Jerome read that in temperate climes, there are more than 133 spiders per square meter of open land with a standard deviation of 4. To test this, he fenced off 31 square meters and carefully counted all the spiders. He found an average of 134.22 spiders per square meter. Which of the following correctly describes the test and hypotheses he should use? A. A z-test with H0:μ≤133, Ha:μ>133 B. A t-test with H0:μ≥133, Ha:μ<133 C. A t-test with H0:μ≤133, Ha:μ>133...

2. a) A) Find the number of atoms per square centimeter in silicon in the (100)...

2. a) A) Find the number of atoms per square centimeter in silicon in the (100) (110) and (111) planes. b) A unit cell of GaAs is shown as below. Calculate the density of GaAs (a=5.65 Angstrom, and the atomic weights of Ga and As are 69.72 and 74.92 g/mol, respectively). c) How many valence electrons are in a tin atom? How many valence electrons are in a Ga atom and an As atom, respectively? A GaAs sample doped with...

The average number of accidents at controlled intersections per year is 4.2. Is this average a...

The average number of accidents at controlled intersections per year is 4.2. Is this average a different number for intersections with cameras installed? The 43 randomly observed intersections with cameras installed had an average of 4.8 accidents per year and the standard deviation was 1.12. What can be concluded at the α α = 0.10 level of significance? For this study, we should use The null and alternative hypotheses would be: H 0 : H 0 : H 1 :...

What will be the width (B in meter) of a square footing to support rectangular column...

What will be the width (B in meter) of a square footing to support rectangular column 40x40 cm and carries a dead load of 614 kN and live load of 477 kN. The net allowable bearing pressure is 180 kPa. The design should be according to (ACI) code with the following parameters: fc’ = 28 MPa, fy = 420 MPa.

A roll of plastic-coated wire has an average of 0.09 flaws per 5-meter length of wire....

A roll of plastic-coated wire has an average of 0.09 flaws per 5-meter length of wire. Suppose a quality control engineer will sample a 5-meter length of wire from a roll of wire 230 meters in length. If no flaws are found in the sample, the engineer will accept the entire roll of wire. a. What is the probability that the roll will be rejected? b. Before examining the sample, what is the probability that there are no flaws in...

There is an average of 1.1 weedy species per square metre in a native grassland. What...

There is an average of 1.1 weedy species per square metre in a native grassland. What is the probability that a square metre has at most 3 weedy species? 0.0378 0.0738 0.9005 0.9743

Suppose that in past years the average price per square foot for warehouses in the United...

Suppose that in past years the average price per square foot for warehouses in the United States has been $32.28. A national real estate investor wants to determine whether that figure has declined now. The investor hires a researcher who randomly samples 49 warehouses that are for sale across the United States and finds that the mean price per square foot is $31.67, with a sample standard deviation of $1.29. At 5% level of significance, test to see if the...

The average American consumes 80 liters of alcohol per year. Does the average college student consume...

The average American consumes 80 liters of alcohol per year. Does the average college student consume more alcohol per year? A researcher surveyed 12 randomly selected college students and found that they averaged 97.6 liters of alcohol consumed per year with a standard deviation of 23 liters. What can be concluded at the the αα = 0.01 level of significance? For this study, we should use Select an answer t-test for a population mean z-test for a population proportion The...

The average number of accidents at controlled intersections per year is 4.3. Is this average less...

The average number of accidents at controlled intersections per year is 4.3. Is this average less for intersections with cameras installed? The 43 randomly observed intersections with cameras installed had an average of 3.7 accidents per year and the standard deviation was 1.47. What can be concluded at the αα = 0.01 level of significance? Can you please explain the steps of how to obtain the P value and test statistic using a graphing calculator?

The average number of accidents at controlled intersections per year is 4.1. Is this average more...

The average number of accidents at controlled intersections per year is 4.1. Is this average more for intersections with cameras installed? The 43 randomly observed intersections with cameras installed had an average of 4.3 accidents per year and the standard deviation was 0.63. What can be concluded at the αα = 0.05 level of significance? For this study, we should use Select an answer z-test for a population proportion t-test for a population mean The null and alternative hypotheses would...

Subjects