Find the interval about the sample mean such that the probability is 0.90 that the true mean lies within the

interval. (When P=90%, t=1.65)





number of trucks sold vs. number of dealerships


70-90 vs. 2


90-110 vs. 11


110-130 .vs 39


130-150 .vs 17


150-170 .vs 9


170-190 .vs 7Find the interval about the sample mean such that the probability is 0.90 that the true mean lies within the
SMALL-SAMPLE CONFIDENCE INTERVAL FOR A POPLATION MEAN





90% Confidence Interval = x-bar +/- 1.65 * s/SQRT(n)


n = NUMBER OF SAMPLES [3]





Cumulative Distribution Function





Student's t distribution with 3 DF





x P( X %26lt;= x )


1.65 0.901247