Fill in the blank: 50% of the area under the standard normal curve is between -0.5 and

Question

nurali · Answer

@phi

nurali · Answer

@hartnn

nurali · Answer

@Directrix

agent0smith · Answer

About 50% of the area under a normal curve falls within ±0.5 standard deviations of the mean.

agent0smith · Answer

Well it's more like ±0.67, but with the way the question was worded... http://blog.theoptionstradingcourse.com/wp-content/uploads/2011/09/normal671.gif

kropot72 · Answer

50% of the area under the standard normal curve is between z = -0.5 and z = 0.874

nurali · Answer

thanks @kropot72

kropot72 · Answer

You're welcome :)

nurali · Answer

@kropot72 The 60th percentile of a normal distribution is 110. The 70th percentile is 120. Find the 90th percentile. please help

nurali · Answer

please help @kropot72

nurali · Answer

please answer @Directrix

nurali · Answer

The 60th percentile of a normal distribution is 110. The 70th percentile is 120. Find the 90th percentile. please help

directrix · Answer

I'll add my work shortly. I got 148.15 as the 90th percentile. Not sure that is correct.

directrix · Answer

I thought we were finished. I still have to enter that other work that supports the answer.

kropot72 · Answer

The 60th percentile is z = 0.253$$z _{60th}=0.253=\frac{110-\mu}{\sigma}$$
The 70th percentile is z = 0.524
$$z _{70th}=0.534=\frac{120-\mu}{\sigma}$$

kropot72 · Answer

The 90th percentile is z = 1.282
After solving for mu and sigma and substituting I got X = 147.97 for the 90th percentile,

nurali · Answer

please help

directrix · Answer

@Nurali   Post this  problem in a new thread. If @kropot72  and I do all this work, we expect to be "paid." :)

kropot72 · Answer

^^

directrix · Answer

Urgent @Nurali  --> Move the question to a new thread so that we can get to work.