At a middle school students in seventh grade want to conduct a survey on the most popular type of pet for students in the grade. The students want to make a generalization based on a sample Which describes how the sample should be chosen?

A: It must be non-random

B: It must be representative

C: It must be selected by a student not in seventh grade

D: It must be selected to include students from each grade of the middle school.

the volume is the product of the area of the base, 3x(3x+4), and the height, 3x-1

step-by-step explanation:

1/2*qr*rs

step-by-step explanation:

they used 313 gallons of paint

< 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)