<p>15 is D because it is the only answer choice which refers to the confidence interval. The other choices allude to the endpoints of the interval, which cannot be determined for sure.</p>
<p>23 uses the formula moe = t* multiplied by sqrt (p (1-p) /n). We arbitrarily assign the value of p = 0.5 when it isn’t given.</p>
<p>t* = 1.645, p = 0.5, 1-p = 0.5, n is our unknown, moe = 0.05.</p>