Question

The dot plots show the number of hours a lightbulb lasts from two different brands.

Which of the following statements is correct?


a. the mean for brand a is the same we the mean for brand b

b. there were more lightbulbs in the dot plot for brand a than in the dot plot for brand b

c. the mean for brand b is higher than the mean for brand a

d. the mean for brand a is higher than the mean for brand b​

Answer 1

C.

Explanation:

I dont really know so hope its right.

Answer 2

C. The mean for brand B is higher than brand A.

Explanation:

What we're looking for is the true statement of these 4.

We already know B is out, because there were 11 lightbulbs on brand B, and 10 on brand A.

Because of that, A is also out, because the means cannot be the same.

As a result, only C and D remain.

Now, add the 10 dots on brand A.

((1000 * 1) + (1100 * 2) + (1200 * 3) + (1300 * 4))/10

(1000 + 2200 + 3600 + 5200)/10

(3200 + 3600 + 5200)/10

(6800 + 5200)/10

12000/10

Brand A has an average of 1200 hours/lightbulb

Then, add the 11 on brand B

((1400 * 1) + (1500 * 4) + (1600 * 2) + (1700 * 1) + (1800 * 1) + (1900 * 1))/11

(1400 + 6000 + 3200 + 1700 + 1800 + 1900)/11

(7400 + 3200 + 1700 + 1800 + 1900)/11

(10600 + 1700 + 1800 + 1900)/11

(12300 + 1800 + 1900)/11

(14100 + 1900)/11

16000/11

Brand B has an average of 1454 hours 27 minutes 16 seconds 364 milliseconds/lightbulb

Comparing the two averages, we come to the realization that D is out because Brand A's average was less than Brand B's.

That leaves C as our answer.