Which of the following is not a requirement of the combinations rule, subscript n baseline upper c subscript requalsstartfraction n exclamation mark over r exclamation mark left parenthesis n minus r right parenthesis exclamation mark endfraction , for items that are all different? choose the correct answer below. a. that r of the n items are selected (without replacement). b. that there be n different items available. c. that order is not taken into account (consider rearrangements of the same items to be the same). d. that order is taken into account (consider rearrangements of the same items to be different sequences).

D. That order is taken into account (consider rearrangements of the same items to be different sequences).

Step-by-step explanation:

is the number of different combinatios of x objects from a set of n elements, given by the following formula.

For example:

Combinations of 2 from a set a,b,c: ab=ba, ac = ca, bc = cb, meaning that the order is not important(ab and ba is the same sequence).

aa, bb, cc are not valid, since there is no replacement.

So the answer for this qustion is:

D. That order is taken into account (consider rearrangements of the same items to be different sequences).

15%

step-by-step explanation:

use the table and count the number of guesses that has two correct answers.

the following are two correct answers

10010, 01100, 11000

a total of 3 numbers having 2 correct guesses out of 20 questions.

probability of getting 2 correct guesses = the number of questions getting 2 correct answers / total number of questions.

= 3/20

to convert it into percent multiply by 100, we get

= 3/20 * 100

= 15%

the answer is 15%

you.

the largest number of the four options is 1.8 x 10-2

you have it in scientific notation.

1.80 x 10-6   = 0.00000180

1.80 x 10-4   = 0.000180 (bigger, or "less small", than the former one)

so

1.8 x 10-2       = 0.0180. as you see. the "less small", or the biggest one of them all.

as you have negative exponent, it means you are dividing 1.8 by 100 (i.e. moving the dot towards left, two times).

if you had positive exponent for the scientific notation, power of tenths, you would be multiplying times 100 (moving the dot towards right) as below:

1.8 x (10)2 = 180

so. if you have negative exponent in scientific notation, move the dot toward left. if it is positive, toward right as many times the exponent tells you.