Merge Note: Answer Questions 1-6 by Using the TI-30XA (or other approved) Calcul

Question

Merge Note: Answer Questions 1-6 by Using the TI-30XA (or other approved) Calculator. IMPORTANT Make sure you carry all decimals until you reach your answer, then round to four decimals 10 12 The weight of a Sth grader is normally distributed with a mean of 74 pounds and a varilance of s7 pounds 2. Let weight, in pounds, be represented by random variable X. 16 Qvestion 1682)-0 1160 Find x2. (Remember the label 2 On the SAT, the average Writing score is 492 points and the average Mathematics score is S23 points. The standard deviation is 73 points on each part of the test. Now su test takers are selected. (See exercise 21 on page 326 of your textbook for a similar problem.) Quesson2 Bhofthe time the umple ,verage Writing scor·should be less than what? ete ember the idel). Starbucks has found that 22% of customers purchase more than one cup of coffee per day from their shops. Suppose you randomly choose 18s of today's Starbucks customers. aiesoon Find the probablity that no less than 31% efthem prchased mers than one cup of coffee bom Stvbucks.

Explanation / Answer

a)

P(68<X<x2) =0.1160

P(X<68)-P(X<x2) =0.1160

P(X<x2) =0.2134-0.1160 =0.0974 (for which z score =1.2965

X =74-1.2965*7.5498 =64.2116

2)

for 85th percentile ; z score =1.0364

hence corresponding score =mean +z*std error =503.5380

3) std error =(p*(1-p)/n)1/2 =0.0305

for normal distribution z score =(X-)/ here mean=       = 74.000 std deviation   == 7.5498

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