Question

As part of a science experiment, Sam recorded the four values shown in the table, but one of them got smudged on his paper. He remembers that the sum of the trials was −1. What was the value that was smudged?
Trials

−9

12

(smudged)

−8


A) 2


B) −2


C) −4


D) 4


PLEASE HELP IM GONNA FAIL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :(

Answer 1

Answer:

D) 4

Step-by-step explanation:

−9 + 12 + (unknown) + −8 = −1

Start by going through and testing each option

−9 + 12 + 2 + −8 =

3 + 2 + −8 =

5 + −8 =

−3

−3 ≠ −1

A) 2 is not possible.

−9 + 12 + −2 + −8 =

3 + −2 + −8 =

1 + −8 =

−7

−7 ≠ −1

B) −2 is not possible.

−9 + 12 + −4 + −8 =

3 + −4 + −8 =

−1 + −8 =

−9

−9 ≠ −1

C) −4 is not possible.

From this, D is looking like the answer. But to be sure, test it.

−9 + 12 + 4 + −8 =

3 + 4 + −8 =

7 + −8 =

−1

−1 = −1

D) 4 is the answer.