Questions: Assume that the readings on the thermometers are normally distributed with a mean of 0°C and standard deviation of 1.00°C. A thermometer is randomly selected and tested. Draw a sketch and find the temperature reading corresponding to P88, the 88th percentile. This is the temperature reading separating the bottom 88% from the top 12%.
Which graph represents P88? Choose the correct graph below.
A.
B.
C.
D.
The temperature for P88 is approximately °C.
(Round to two decimal places as needed.)
Transcript text: Assume that the readings on the thermometers are normally distributed with a mean of $0^{\circ}$ and standard deviation of $1.00^{\circ} \mathrm{C}$. A thermometer is randomly selected and tested. Draw a sketch and find the temperature reading corresponding to $\mathrm{P}_{88}$, the 88th percentile. This is the temperature reading separating the bottom $88\%$ from the top $12\%$.
Which graph represents $P_{88}$ ? Choose the correct graph below.
A.
B.
C.
D.
The temperature for $\mathrm{P}_{88}$ is approximately $\square$ $\square^{\circ}$.
(Round to two decimal places as needed.)
Solution
Solution Steps
Step 1: Identify the Given Information
The problem states that the readings on the thermometers are normally distributed with a mean (μ) of 0°C and a standard deviation (σ) of 1.00°C. We need to find the temperature reading corresponding to the 88th percentile (P88).
Step 2: Understand the Percentile
The 88th percentile (P88) means that 88% of the data falls below this value. In terms of the standard normal distribution, we need to find the z-score that corresponds to the cumulative probability of 0.88.
Step 3: Find the Z-Score
Using a standard normal distribution table or a calculator, we find the z-score that corresponds to a cumulative probability of 0.88. The z-score for 0.88 is approximately 1.175.
Step 4: Convert Z-Score to Temperature
To convert the z-score to the actual temperature, we use the formula:
\[ X = \mu + z \cdot \sigma \]
Substituting the values:
\[ X = 0 + 1.175 \cdot 1.00 \]
\[ X = 1.175 \]
Step 5: Choose the Correct Graph
The correct graph should show the area to the left of the z-score 1.175, which represents 88% of the data. This corresponds to graph D.
Final Answer
The temperature for \( P_{88} \) is approximately \( 1.18^\circ \) (rounded to two decimal places). The correct graph is D.