Answer:
Step-by-step explanation:
<u>Mean of four numbers a, b, c, and d is 8:</u>
- (a + b + c + d)/4 = 8
- ⇒ a + b + c + d = 32
<u>Mean of seven numbers x, y, z, a, b, c and d is 12:</u>
- (x + y + z + a + b + c + d)/7 = 12
<u>Substitute the sum of 4 numbers:</u>
- x + y + z + 32 = 7*12
- x + y + z = 84 - 32
- x + y + z = 52
<u>Mean of x, y and z is:</u>
Y=31.2
X=15.6
I rounded both to the nearest tenth place.
Answer:
B. 4200
Step-by-step explanation:
A suitable calculator can add the terms for you. (See attached)
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The first term is 69, and the common difference is 75-69 = 6. The general term is ...
an = a1 +d(n -1)
an = 69 +6(n -1)
Then the 28th term is ...
a28 = 69 +6(27) = 231
The average term is (a28 +a1)/2 = (231 +69)/2 = 150.
The sum is the number of terms multiplied by the average term:
sum = 28×150= 4200