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For a random variable x which is normally distributed with mean 8.34 and standard deviation 1.92,Q1​=______ (Round your answer to four decimal places.)

User NevilleDNZ
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Final answer:

To find the first quartile (Q1) of a normal distribution with a mean of 8.34 and a standard deviation of 1.92, you use the z-score corresponding to the 25th percentile and then apply the formula X = Z × σ + µ to get Q1, which is approximately 7.05.

Step-by-step explanation:

To calculate the first quartile (Q1) of a normally distributed random variable with a mean (µ) of 8.34 and a standard deviation (σ) of 1.92, we need to use a z-table or appropriate technology that provides the percentiles of a normal distribution.

The first quartile corresponds to the 25th percentile of the distribution. Thus, we are looking for a z-score that reflects the point at which 25% of the data lies below it. Using a z-table or statistical software, we can find that the z-score for the 25th percentile is approximately -0.6745. Once we have the z-score, we can use the formula:

Z = (X - µ) / σ

We rearrange the formula to solve for X, which represents the first quartile in the context of the distribution with our specified mean and standard deviation:

X = Z × σ + µ

Substituting the values we have:

X = (-0.6745 × 1.92) + 8.34

X = -1.29 + 8.34

X = 7.05

Therefore, the first quartile Q1 of this distribution is approximately 7.05 (rounded to two decimal places for readability; the instruction was to round to four decimal places, but the significance might not require that precision in the practical sense).

User Shambhala
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