MATH 1342 04P/05P exam_2 Post_Quiz

A coin was flipped 1000 times, and 550 times it showed up heads. Do you think the coin is biased?

• No

• Yes

Tags

CCSS.7.SP.C.6

Suppose, the probability of dangerous fires are rare (1%) but smoke is fairly common (10%) due to barbecues, and 90% of dangerous fires make smoke.

What is the probability of dangerous Fire given there is Smoke?

• 0.9

• 0.5

• 0.09

• 1.0

Tags

CCSS.HSS.CP.B.6

Given two fair dices, what is the probability that two dices sum to 8?

• 0.3189

• 0.1389

• 0.01389

• 0.5

Three ants are sitting at the corners of an equilateral triangle. Each ant randomly picks a direction and starts moving along the edge of the triangle. What is the probability that none of the ants collide?

• 0.25

• 0.50

• 0.75

• 1.00

Answer explanation

Each ant has two possible ways to go: the edge on its left L and the edge on its right R.

Now the only way no ant will collide is if they all walk in the same direction along the triangle (assuming they all move at the same speed).

Overall the ways how the ants can move are:

LLL

LLR

LRL

RLL

LRR

RLR

RRL

RRR

We have a total of 8 ways how the 3 Ants can move, out of these, only RRR and LLL are the ways by which the Ants will never meet. So the probability of it is,

2/8 = 0.25

Let Z be a standard normal random variable. Use the standard normal table to

determine the value of c.

P ( 0.98 ≤ Z ≤ c ) = 0.1470

• 213

• 3.12

• 2.13

• 312

Tags

CCSS.HSS.ID.A.4

A psychologist has designed a questionnaire to measure individuals' aggressiveness. Suppose that the scores on the questionnaire are normally distributed with a standard deviation of 80. Suppose also that exactly 10% of the scores exceed 800. Find the mean of the distribution of scores.

• No correct answer

• 800

• 679.5

• 697.5

Suppose that pulse rates among healthy adults are normally distributed with a mean of 81 beats/minute and a standard deviation of 8 beats/minute.

What proportion of healthy adults have pulse rates that are more than

93 beats/minute?

• 0.0846

• 0.0668

• 0.0478

• −0.78

Answer explanation

We need to apply z score formual:

z score = (x-mean)/standard deviation:

So,

P(x>93)

= P(z > (93-81)/8)

= P (z > 1.5)

= 1- P(z < 1.5)

= 1-0.9332

= 0.0668

Tags

CCSS.HSS.ID.A.4

Suppose we want to choose 6 colors, without replacement, from 10 distinct colors.

How many ways can this be done, if the order of the choices is taken into consideration?

• 252100

• 151200

• 60000

• Can not be done

Answer explanation

10!/(10-6)!

if order Matters:

nPr formula

Suppose we want to choose 6 colors, without replacement, from 10 distinct colors.

How many ways can this be done, if the order of the choices is not taken into consideration?

• 520

• 100

• 156

• 210

Answer explanation

10!/((10-6)!6!)

if order does NOT matter:

nCr formula

Find the variance, Var(X) of X.

• 51.5

• 152.6

• 112.75

• 121.75