Janet wanted to determine her average phone call length over 90 days. She collected the phone bills and randomly picked ten entries to look at. The phone call lengths, in minutes, are shown below. 3, 9, 17, 9, 11, 3, 11, 3, 17, 3

Assuming that the sample was representative of all the entries on the bills, what was the mean number of minutes over 90 days?

A. 7

B. 10

C. 8.6

Mean is the average. Add the minutes together and divide by 10.

86 /10 = 8.6

The answer is c

60%

< xcy ≅ < xby

step-by-step explanation:

in δcax and δbax,

so, δcax ≅ δbax (side-angle-side or sas)

since δcax ≅ δbax, we can conclude < acx ≅ < abx

in δacy and δaby,

so, δacy ≅ δaby (side-angle-side or sas)

since δacy ≅ δaby, we can conclude < acy ≅ < aby

now,

< acy ≅ < aby

=> < acx + < xcy ≅ < abx + < xby

=> < acx + < xcy ≅ < acx + < xby   (since < acx ≅ < abx already proved above)

subtracting < acx from both sides, we get

< acx + < xcy -< acx ≅ < acx + < xby -< acx

cancelling out < acx and -< acx from both sides, we get

< xcy ≅ < xby (proved)