A salesman normally makes a sale​ (closes) on 75​% of hispresentations. Assuming the presentations are​ independent, findthe probability of each of the following.
​a) He fails to close for the first time on his fifthattempt.
​b) He closes his first presentation on his fourth attempt.
​c) The first presentation he closes will be on his secondattempt.
​d) The first presentation he closes will be on one of his firstthree attempts.
A manufacturer of game controllers is concerned that itscontroller may be difficult for​ left-handed users. They set out tofind lefties to test. About 13​% of the population is​ left-handed.If they select a sample of 6 customers at random in their​ stores,what is the probability of each of the outcomes described in partsa through f​ below?
a) The first lefty is the fourth person chosen.
The probability is _____________
​(Round to four decimal places as​ needed.)
The probability model below describes the number of repair callsthat an appliance repair shop may receive during an hour. Completeparts a and b below.
Repair Calls 1 2 3 4
Probability .1 .4 .3 .2
​b) What is the standard​ deviation?
The standard deviation is ____________
​(Round to two decimal places as​ needed.)
