Question

There are many regulations for catching lobsters off the coast of New England including required permits, allowable gear, and size prohibitions. The Massachusetts Division of Marine Fisheries requires a minimum carapace length measured from a rear eye socket to the center line of the body shell. For a particular local municipality, any lobster measuring less than 3.37 inches must be returned to the ocean. The mean carapace length of the lobsters is 4.01 inches with a standard deviation of 2.13 inches. A random sample of 60 lobsters is obtained.
Required:
What is the probability that the sample mean carapace length is more than 4.25 inches?

Answer 1

Answer:

Probability that the sample mean carapace length is more than 4.25 inches = 0.9993

Step-by-step explanation:

Given - There are many regulations for catching lobsters off the coast

             of New England including required permits, allowable gear, and

             size prohibitions. The Massachusetts Division of Marine Fisheries

             requires a minimum carapace length measured from a rear eye

             socket to the center line of the body shell. For a particular local

             municipality, any lobster measuring less than 3.37 inches must

             be returned to the ocean. The mean carapace length of the  

             lobsters is 4.01 inches with a standard deviation of 2.13 inches.

             A random sample of 60 lobsters is obtained.

To find - What is the probability that the sample mean carapace length

              is more than 4.25 inches?

Proof -

Given that, μ = 4.01, σ = 2.13 , n = 60

Now,

μₓ⁻ = σ / √n

    = $\frac{2.13}{\sqrt{60} }$

    = $\frac{2.13}{7.746}$ = 0.275

⇒μₓ⁻ = 0.275

Now,

P(X⁻ > 3.37) = 1 - P( X⁻ <  3.37)

                   = 1 - P(z <  $\frac{3.37 - 4.25}{0.275}$ )

                   = 1 - P( z < -3.2 )

                   = 1 - 0.0007

                   = 0.9993

⇒P(X⁻ > 3.37) = 0.9993

∴ we get

Probability that the sample mean carapace length is more than 4.25 inches = 0.9993