Suppose scores on a standardized test taken by future doctors are normally distributed w/ a mean of 10.5 and a standard deviation of 2.2....

...Approximately 70% of the future doctors scored less than what score?

The teacher says that the answer is 11.6 and honestly, I don t see why? Please explain with work shown towards why it is 11.6? B/c I have tried so many times messing with the standardizing data formula and I cannot seem to figure it out...I don t know what I am doing wrong....Please help?

Question

Suppose scores on a standardized test taken by future doctors are normally distributed w/ a mean of 10.5 and a standard deviation of 2.2....

...Approximately 70% of the future doctors scored less than what score?

The teacher says that the answer is 11.6 and honestly, I don t see why? Please explain with work shown towards why it is 11.6? B/c I have tried so many times messing with the standardizing data formula and I cannot seem to figure it out...I don t know what I am doing wrong....Please help?

goldandpinkiscool · Answer

@Helpmeeasetjx @helpkay

kropot72 · Answer

The first step is to use a normal distribution table to find the z-score that corresponds to a cumulative probability of 0.7. The z-score for a cumulative probability of 0.7 is 0.525.
Now we can write:
$$\large 0.525=\frac{X-10.5}{2.2}$$
Next you just need to solve to find the value of X.

goldandpinkiscool · Answer

All right thanks @kropot72

kropot72 · Answer

You're welcome :)

goldandpinkiscool · Answer

@kropot72 u think u can help me with another problem?

kropot72 · Answer

Sorry, I need to log out now. Please post as a new problem.