Finding the mean is you have to add it all up:
49+55+52+46+47+42+38= 328
The divide it by the amount of numbers so, 329/7= 47.
Subtract 47 from every number then, but even if you get a negative number you gotta keep it a positive so just ignore it if you get a negative answer when subtracting, once you do that you would add up those answers you got so;
2+8+5+1+0+5+9= 30
Then divide it again, 30/7
Which then you get the M.A.D which is 4.3, rounded to the nearest ten.
You know a1.
So find a2, a3, and so on until a7.
a(1) = 12
a(2) = 16
a(3) = 20
a(4) = 24
a(5) = 28
a(6) = 32
a(7) = 36
Each is 4 more than the previous.
area of a triangle = 1/2 base x height
56.4 = 1/2 x 12 x height
56.4 = 6 x height
height = 56.4 /6 = 9.4cm
um what
sory not understand from finland good luck
B=5
Hope this helps!
Vote me brainliest!