Answer:
A. 288pi in^3
Step-by-step explanation:
s
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3a+11=7a-13
move 7a to the other side
sign changes from +7a to -7a
3a-7a+11= 7a-7a-13( combine like terms)
3a-7a+11= -13
-4a+11= -13
move 11 to the other side
sign changes from +11 to -11
-4a+11-11= -13-11
-4a= -13-11
-4a= -24
divide both sides by -4 to get a by itself
-4a/-4= -24/-4
Answer: a= 6
Answer:
11 yrs
Step-by-step explanation:
Mean = sum of ages/number of ages
Let the age of the seventh girl be A
Given the addition of the age of the seventh girl will make the mean of the ages be 13,
So,
13 = 17+8+12+15+15+13+A/7
Add up the ages
13 = 80 + A /7
Cross multiply
80 + A = 13 x 7
80 + A = 91
Subtract 80 from both sides to isolate A
80 - 80 + A = 91 - 80
A = 11
The age of the seventh girl is 11
