((5x5)/2)x2=50 square ft
(8x5)x2= 80 square ft
8x7= 56 square ft
50+80+56=186 square ft
D) 186 square ft
A geometric sequence is a sequence in which there is a common ratio between any two consecutive terms. In this case if X:Y:Z are in the ratio of 2:7:8 the multiplying by a constant k, we have X=2k, Y= 7k and Z=8k.
Then if X, Y-12, Z form a Geometric sequence, it means X/Y-12=Y-12/Z which is the same as 2k/7k-12=7k-12/8k if we cross multply, we get
16k²= 49k²-168k +144
33k²-168k+144 =0 solving for k
k = 4 or 1.091 if we take the whole number to find the values of X,Y and z,
X= 8, Y= 28 and Z=32
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1) Turn off Wifi
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3) Take picture of answer or remember it
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The expression in company B represents that is is in arithmetic progression where first term is 42000 and common difference is 1800 . So we have to use the formula of sum of n terms which is

Where a is the first term, n is the nth term, d is the common difference
On substituting there values,we will get

= 15(84000+52200) = 15*136200 =2043000
And for company A, it is

Difference between them =2043000-2002500= 40500
So the correct option is the second option .