Question

7. (6 points) The number of vehicles passing through a busy intersection between 8:00 a.m. and 10:00 a.m. was observed and recorded on every weekday morning of the last year. The sample mean is found to be * = 675 and the sample standard deviation is 8 = 25. (a) Approximately what proportion of observations are between 625 and 725 cars? (b) Approximately what proportion of observations are greater than 750 cars?

Answer 1

Date: Page No. : Cuven z = 675 P[ 625 <X <725] 25-675 <zic 725-675 25 VYTETIT - P[ -2 -242] = RESEORFOLL2T = P[z<2 ] - Plzc-2] using formular Placzeb] =pIzeb]-p 1 = 0.97725- 0.02275 (using Normal = 0.9545 So the proportion of obsercation are between 625 and 725 cars is 0.9545. PEX >750] = [X-M > 750-675) - Pł 272 ] = I-P[222] 25 - from a Litable - 0.97725 0.02275 observations are is 0.022750 The proportion than 750 of car greater