Math Is Fun Forum

A study was conducted to determine the proportion of people who dream in black and white instead of color. Among 315 people over the age of 55, 72 dream in black and white, and among 285 people under the age of 25, 13 dream in black and white. Use a 0.05 significance level to test the claim that the proportion of people over 55 who dream in black and white is greater than the proportion for those under 25.

1) Identify the test statistic. z=
2)Test the claim by constructing an appropriate confidence interval. The 90% confidence interval is _<(p1-p2)<_.

I know what the formula is, I just can't figure out figure it out by hand.

Thanks!!