Question

Cory is a birdwatcher. He estimates that 30% of the birds hesees are American robins, 20% are dark-eyed juncos, and 20%are song sparrows. He designs a simulation.Let 0, 1, and 2 represent American robins.Let 3 and 4 represent dark-eyed juncos.Let 5 and 6 represent song sparrows.Let 7, 8, and 9 represent other birds.The table shows the simulation results.What is the probability that at least one of the next five birdshe sees is a robin?

Answer 1

Given:

Cory is a birdwatcher. He estimates that 30% of the birds he sees are American robins, 20% are dark-eyed juncos, and 20% are song sparrows. He designs a simulation.

Let 0, 1, and 2 represent American robins.

Let 3 and 4 represent dark-eyed juncos.

Let 5 and 6 represent song sparrows.

Let 7, 8, and 9 represent other birds.

Required:

What is the probability that at least one of the next five birds

he sees is a robin?

Explanation:

The probability

$=\frac{\text{ Favorable number of cases}}{\text{ Total number of cases}}$

Using the above representations, the numbers that represent an occurrence of seeing at least one robin in the next 5 birds are:

01611, 26343, 87408, 08889, 58822, 49003, 49116, 67970, 71890, 01595, 30500, 91971, 39440, 28893, 51995.

The number of occurences is 15.

The number of simulation equals 20.

So, the probability of seeing at least one robin is:

$\begin{gathered} P=\frac{15}{20} \\ =\frac{3}{4} \\ =0.75 \end{gathered}$

Answer:

Option B is correct.