According to moebs services inc., an individual checking account at u. s. community banks costs these banks between $175 and $200 per year. suppose that the average annual cost of all such checking accounts at u. s. community banks is $190 with a standard deviation of $20. find the probability that the average annual cost of a random sample of 100 such checking accounts at u. s. community banks is

0.1855

Step-by-step explanation:

Assuming normal distribution, Sampling mean = $190

Sampling standard deviation = = $2

a) Probability that the average annual cost of a random sample of 100 such checking accounts at U.S. community banks is less than $187 = P(X < 187)

= P(Z < (187 - 190)/2)

= P(Z < -1.5)

= 0.0668

b) Probability that the average annual cost of a random sample of 100 such checking accounts at U.S. community banks is more than $193.5

= 1 - P(X < 193.5)

= 1 - P(Z < (193.5 - 190)/2)

= 1 - P(Z < 1.75)

= 1- 0.9599

= 0.0401

c) Probability that the average annual cost of a random sample of 100 such checking accounts at U.S. community banks is between $191.70 to 194.5 = P(X < 194.5) - P(X <191.7)

= P(Z < (194.5 - 190)/2) - P(Z < (191.7-190)/2)

= P(Z < 2.25) - P(Z < 0.85)

= 0.9878 - 0.8023

= 0.1855

this story was prepared by jim

mccullaugh in los angeles and

al stewart in new york.

new york the colossal success of "top gun" appears to have dramatically altered madison avenue's

perception of corporate sponsorship

of home video projects.

the paramount home video re- lease, featuring a 60- second diet

pepsi spot, was by no means the

first prerecorded video to carry an advertiser's plug, but it was the

first major theatrical release to do so. in the aftermath of the title's

success, paramount is widely ex- pected to ink a similar deal for

"crocodile dundee" or "star trek

iv" or both.

corporate america's new attraccds push british

recording sales

to 19% gain

london fueled by the compact

disk boom, the value of u.k. manu- facturer shipments of recordings

rose 19% in the 12 -month period ended march 1987, according to the

british phonographic industry.

total value of u.k. shipments for

the period was $755 million for all

configurations. (all value figures

are based on an exchange rate of

$1.68 to the pound sterling.)

cd sales totaled 10.7 million units

worth $121.3 million- compared

with 3.7 million units worth $39.5

million in the prior 12 months -and

accounted for two -thirds of the

overall gain in trade value. at present growth rates, says the bpi, cd

sales for calendar 1987 will reach 20

(continued on page 79)

step-by-step explanation: