Chapter 7, section 7.2, question p9 the process for manufacturing a ball bearing results in weights that have an approximately normal distribution with mean 0.15 g and standard deviation 0.005 g. a. if you select one ball bearing at random, what is the probability that it weighs less than 0.149 g? (round to four decimal places) b. if you select four ball bearings at random, what is the probability that their mean weight is less than 0.149 g? (round to four decimal places) c. if you select ten ball bearings at random, what is the probability that their mean weight is less than 0.149 g? (round to four decimal places)

a. Let be a random variable representing the weight of a ball bearing selected at random. We're told that , so

where . This probability is approximately

b. Let be a random variable representing the weight of the -th ball that is selected, and let be the mean of these 4 weights,

The sum of normally distributed random variables is a random variable that also follows a normal distribution,

so that

Then

c. Same as (b).

answer

a,b, and d

explanation

a reflection angle is more than

but less than;

an angle that measures

is a reflex angle.(true)

an angle that measures less than

is acute.(true)

provided we are considering angles greater or equal to zero.

an acute angle lies in the range.

an obtuse angle is less than 180° but more than 90°

an angle that measures 300° is obtuse (false)

an angle that measures 65° is an acute angle.(true)

2 1/2 feet

step-by-step explanation: