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Obtain the following probabilities for the standard normal distribution. a. \(P(z>-.98)\) b. \(P(-2.47 \leq z \leq 1.29)\) c. \(P(0 \leq z \leq 4.25)\) d. \(P(-5.36 \leq z \leq 0)\) e. \(P(z>6.07)\) f. \(P(z<-5.27)\)

Short Answer

Expert verified
a. 0.8365, b. 0.8946, c. 0.5, d. 0.5, e. 0, f. 0

Step by step solution

01

- Understand the standard normal distribution table

The standard normal distribution table shows the probability that a normally distributed random variable Z, with mean equal to 0 and variance equal to 1, is less than or equal to z. It is used to find the probability that a statistic is observed below, above, or between values.
02

- Calculate Probability for \(P(z>-.98)\)

The table gives us the probability that a Z-score is less than -0.98 (i.e. \(P(Z<-0.98)\)). And because the total probability under the bell curve is 1, the probability that a Z-score is greater than -0.98 is \(1 - P(Z<-0.98)\). Using the Z-score table, we find that \(P(Z<-0.98) = 0.1635\). Therefore, \(P(Z > -0.98) = 1 - 0.1635 = 0.8365\).
03

- Calculate Probability for \(P(-2.47 \leq z \leq 1.29)\)

To find this, we need to find \(P(Z \leq 1.29)\) and \(P(Z \leq -2.47)\), and then subtract the two. From the table, \(P(Z \leq 1.29) = 0.9015\) and \(P(Z \leq -2.47) = 0.0069\). Therefore, the answer is \(0.9015 - 0.0069 = 0.8946\).
04

- Calculate Probability for \(P(0 \leq z \leq 4.25)\)

This is equivalent to finding \(P(Z \leq 4.25)\). Since the standard normal distribution is symmetric about zero, the probability that Z is less than 0 is 0.5. Thus, we find from the table that \(P(Z \leq 4.25) = 1\), so the answer is \(1 - 0.5 = 0.5\).
05

- Calculate Probability for \(P(-5.36 \leq z \leq 0)\)

The probability that Z is less than 0 is 0.5. And the probability that Z is less than -5.36 is basically 0, because -5.36 is many standard deviations away from the mean. Therefore, the answer is \(0.5 - 0 = 0.5\).
06

- Calculate Probability for \(P(z > 6.07)\) and \(P(z < -5.27)\)

For any Z-score that is more than 5 standard deviations away from the mean, the probabilities are practically 0. Therefore, \(P(Z > 6.07) = 0\) and \(P(Z < -5.27) = 0\)

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