1. ## Please do Help me

1. Blood pressure is described by two numbers: systolic pressure and diastolic pressure (measured in mm of Hg). A study showed systolic pressure to be normally distributed with a mean of 125 and a standard deviation of 15, and the diastolic pressure to be normally distributed with a mean of 84 and a standard deviation of 9. Two study participants are randomly selected and their blood pressures are measured. The first participant had a systolic reading of 100 mm of Hg, while the second had a diastolic reading of 75 mm of Hg. Which participant had a lower reading with regard to the study population?

8. The annual number of earthquakes, the world over, is a random variable having approximately a normal distribution with m=20.8(mutte symbol). What is the standard deviation of this distribution if the probability is 0.40 that there will be less than 15 earthquakes?

2. Originally Posted by hidaja16
1. Blood pressure is described by two numbers: systolic pressure and diastolic pressure (measured in mm of Hg). A study showed systolic pressure to be normally distributed with a mean of 125 and a standard deviation of 15, and the diastolic pressure to be normally distributed with a mean of 84 and a standard deviation of 9. Two study participants are randomly selected and their blood pressures are measured. The first participant had a systolic reading of 100 mm of Hg, while the second had a diastolic reading of 75 mm of Hg. Which participant had a lower reading with regard to the study population?

8. The annual number of earthquakes, the world over, is a random variable having approximately a normal distribution with m=20.8(mutte symbol). What is the standard deviation of this distribution if the probability is 0.40 that there will be less than 15 earthquakes?

1. Convert X = 100 into a z-score: $Z = \frac{100 - 125}{15} = \, ....$

Convert Y = 75 into a z-score: $Z = \frac{75 - 84}{9} = \, ....$.

Which z-score is lower .....?

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8. Pr(X < 15) = 0.40.

Now get the value of z* such that Pr(Z < z*) = 0.40.

Then $z^* = \frac{15 - 20.8}{\sigma}$.

Solve for $\sigma$.