If the table below represents a probability model based on observed frequencies, what is the value of x

?

This table shows a probability model for the letters Y, C, A, R, E, and S based on observed frequencies.
Y C A R E S
P(Y) 0.25 0.18 0.30 0.17 x

(1 point)
Responses

0.20
0.20

0.10
0.10

1
1

0.01

1 answer

To find the value of \( x \) in the probability model, we need to remember that the sum of all probabilities must equal 1.

From your table, we have the probabilities:

  • \( P(Y) = 0.25 \)
  • \( P(C) = 0.18 \)
  • \( P(A) = 0.30 \)
  • \( P(R) = 0.17 \)
  • \( P(E) = x \)
  • \( P(S) = 1 - (0.25 + 0.18 + 0.30 + 0.17 + x) \)

We can set up the equation as follows:

\[ 0.25 + 0.18 + 0.30 + 0.17 + x + P(S) = 1 \]

First, we calculate the sum of the known probabilities:

\[ 0.25 + 0.18 + 0.30 + 0.17 = 0.90 \]

This means:

\[ 0.90 + x + P(S) = 1 \]

If we denote \( P(S) \) as \( 1 - (0.90 + x) \):

\[ P(S) = 1 - 0.90 - x \]

Since \( P(S) \) should also be a probability, it must be non-negative. Let's then write \( P(S) = 0.10 - x \) such that \(0.10 - x = 0\) and set the limits:

This means that:

\[ 0.10 \geq x \geq 0 \]

So, the only possible non-negative values of \( x \) that fit the probability model must be equal to:

\[ x = 0.10 \]

In the options provided, the value of \( x \) is therefore:

0.10.