Confidence Interval

[tomato]

I'm having trouble figuring these two problems out. I'm hoping someone can help me :?

(1) Mean = 237.1, standard dev = 39.2; find a 95% confidence interval for x

(2) For a distribution with sigma = 38.90, how large a sample must we draw to estimate the true mean to within 5 units with 95% confidence?

Thanks

 

[tkhunny]

Mean + (Z-score * Standard Deviation) = Upper Bound
Mean - (Z-score * Standard Deviation) = Lower Bound