Using the given information, the value of Σfd is 800
<h3>Calculating mean using Assumed mean </h3>
From the question, we are to determine the value of Σfd
The formula for mean, using the assumed mean method is given by
Where 
is the mean
A is the assumed mean
From the given information,
Putting the parameters into the equation, we get
Hence, the value of Σfd is 800
Learn more on Mean here: brainly.com/question/20118982
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Answer:
the common ratio is either 2 or -2.
the sum of the first 7 terms is then either 765 or 255
Step-by-step explanation:
a geometric sequence or series of progression (these are the most common names for the same thing) means that every new term of the sequence is created by multiplying the previous term by a constant factor which is called the common ratio.
so,
a1
a2 = a1×f
a3 = a2×f = a1×f²
a4 = a3×f = a1×f³
the problem description here tells us
a3 = 4×a1
and from above we know a3 = a1×f².
so, f² = 4
and therefore the common ratio = f = 2 or -2 (we need to keep that in mind).
again, the problem description tells us
a2 + a4 = 30
a1×f + a1×f³ = 30
for f = 2
a1×2 + a1×2³ = 30
2a1 + 8a1 = 30
10a1 = 30
a1 = 3
for f = -2
a1×-2 + a1×(-2)³ = 30
-10a1 = 30
a1 = -3
the sum of the first n terms of a geometric sequence is
sn = a1×(1 - f^(n+1))/(1-f) for f <>1
so, for f = 2
s7 = 3×(1 - 2⁸)/(1-2) = 3×-255/-1 = 3×255 = 765
for f = -2
s7 = -3×(1 - (-2)⁸)/(1 - -2) = -3×(1-256)/3 = -3×-255/3 =
= -1×-255 = 255
-56
Explain 9x7 is 56 then you add a negative. Please thanks and brainliest if correct!
Answer:
the answer is B. 75
Step-by-step explanation:
We have that
scale factor=1 in/2.5 miles
<span>the actual area of a lake is 12 square miles
</span>we know that
[area on the map]=[scale factor]²*[area actual]
[area on the map]=[1/2.5]²*[12]-----> 1.92 in²
the answer is
1.92 in²
