On a planet far far away from Earth, IQ of the ruling species is normally distributed with a mean of 103 and a standard deviation of 15. Suppose one individual is randomly chosen. Let X = IQ of an individual. a. What is the distribution of X? X - N( b. Find the probability that a randomly selected person's IQ is over 92. Round your answer to 4 decimal places. c. A school offers special services for all children in the bottom 7% for IQ scores. What is the highest IQ score a child can have and still receive special services? Round your answer to 2 decimal places.

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### IQ Distribution and Statistics on a Distant Planet

#### Background
On a planet far away from Earth, the IQ of the ruling species is normally distributed with a mean of 103 and a standard deviation of 15. Suppose one individual is randomly chosen. Let \( X \) represent the IQ of an individual.

#### Questions and Answers

**a. What is the distribution of \( X \)?**

The distribution of \( X \) is given by:

\[ X \sim N(\text{mean}, \ \text{standard deviation}) \]

Input the respective mean and standard deviation into this normal distribution formula.

**b. Find the probability that a randomly selected person's IQ is over 92.**

To find this probability, use the standard normal distribution. You can find the Z-score using the following formula:
 
\[ Z = \frac{X - \mu}{\sigma} \]

where \( \mu \) is the mean (103) and \( \sigma \) is the standard deviation (15). After calculating the Z-score for 92, you can use a Z-table or statistical software to determine the probability. Round your answer to 4 decimal places.

**c. A school offers special services for all children in the bottom 7% for IQ scores. What is the highest IQ score a child can have and still receive special services?**

To find this IQ score, you will need to determine the Z-score corresponding to the bottom 7% of the normal distribution. Use the inverse of the normal distribution (i.e., the Z-table) to find this value, then convert it back to the original IQ scale:

\[ X = \mu + Z \sigma \]

Round your answer to 2 decimal places.

**d. Find the Inter Quartile Range (IQR) for IQ scores.**

The IQR represents the range between the 25th percentile (Q1) and the 75th percentile (Q3). You can find Q1 and Q3 by looking up the Z-scores for 0.25 and 0.75, respectively, and converting these back to the original IQ scale.

Calculate using the formulas:

\[ Q1 = \mu + Z_{0.25} \sigma \]
\[ Q3 = \mu + Z_{0.75} \sigma \]
\[ \text{IQR} = Q3 - Q1 \]

Round your answers to 2 decimal places.


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Transcribed Image Text:### IQ Distribution and Statistics on a Distant Planet #### Background On a planet far away from Earth, the IQ of the ruling species is normally distributed with a mean of 103 and a standard deviation of 15. Suppose one individual is randomly chosen. Let \( X \) represent the IQ of an individual. #### Questions and Answers **a. What is the distribution of \( X \)?** The distribution of \( X \) is given by: \[ X \sim N(\text{mean}, \ \text{standard deviation}) \] Input the respective mean and standard deviation into this normal distribution formula. **b. Find the probability that a randomly selected person's IQ is over 92.** To find this probability, use the standard normal distribution. You can find the Z-score using the following formula: \[ Z = \frac{X - \mu}{\sigma} \] where \( \mu \) is the mean (103) and \( \sigma \) is the standard deviation (15). After calculating the Z-score for 92, you can use a Z-table or statistical software to determine the probability. Round your answer to 4 decimal places. **c. A school offers special services for all children in the bottom 7% for IQ scores. What is the highest IQ score a child can have and still receive special services?** To find this IQ score, you will need to determine the Z-score corresponding to the bottom 7% of the normal distribution. Use the inverse of the normal distribution (i.e., the Z-table) to find this value, then convert it back to the original IQ scale: \[ X = \mu + Z \sigma \] Round your answer to 2 decimal places. **d. Find the Inter Quartile Range (IQR) for IQ scores.** The IQR represents the range between the 25th percentile (Q1) and the 75th percentile (Q3). You can find Q1 and Q3 by looking up the Z-scores for 0.25 and 0.75, respectively, and converting these back to the original IQ scale. Calculate using the formulas: \[ Q1 = \mu + Z_{0.25} \sigma \] \[ Q3 = \mu + Z_{0.75} \sigma \] \[ \text{IQR} = Q3 - Q1 \] Round your answers to 2 decimal places. This section
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