For example, answering correctly the questions 1,2,3,4,5,6,7,8 is the same outcome as answering 2,1,3,4,5,6,7,8. So we use the combinations formula to solve this problem.

Combinations formula:

$C_{n,x}$ is the number of different combinations of x objects from a set of n elements, given by the following formula.

$C_{n,x} = \frac{n!}{x!(n-x)!}$

"There are 15 questions on an exam. In how many ways can the exam be answered with exactly 8 answers correct?"

Combinations of 8 questions from a set of 15. So

$C_{15,8} = \frac{15!}{8!(15-8)!} = 6435$

The exam can be answered with exactly 8 answers correct in 6435 ways.

5 0

3 years ago

Penny has 139 postcards in her collection. Abe has 48 postcards in his collection. Then Abe gives his collection away. He divide

erik [133]

Answer:

145

Step-by-step explanation:

Divide 48 by 7 = 6≅. then add 6 to 139. 145

5 0

3 years ago

What is the rate of change of the linear relationship modeled in the table? (4 points) x y −2 5 −1 4 0 3 1 2 a −2 b −1 c negativ

Ostrovityanka [42]

Answer:

rate of change=slope= y2-y1/x2-x1

Step-by-step explanation:

x: -2|-1|0|1

y : 5|4|3|2

so choose 2 ordered pairs. in this case, we will choose (-2,5) and (-1,4)

now we plug them in: $\frac{4-5}{-1-(-2)}$

4-5=-1

-1-(-2)=1

so -1/1 is equal to -1, meaning it's answer option b.

4 0

3 years ago

Read 2 more answers