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
A large company wanted to know how the average salary of their employees had changed over the last year. the results of their study had a p-value of 0.12and showed that the average salary had increased by $1,500 from $20,000 to $21,500. The results were practically significant but not statistically significant.
Answer:
Between 15.95 ounces and 16.15 ounces.
Step-by-step explanation:
We have the following value m, being the mean, sd, being the standard deviation and n, the sample size:
m = 16.05
sd = 0.1005
n = 4
We apply the formula of this case, which would be:
m + - 2 * sd / (n ^ 1/2)
In this way we create a range, replacing we have:
16.05 + 2 * 0.1005 / (4 ^ 1/2) = 16.1505
16.05 - 2 * 0.1005 / (4 ^ 1/2) = 15.9495
Which means that 95% of all samples are between 15.95 ounces and 16.15 ounces.
You are adding two each time
For this case we have the following conversion:
1 pound = 16 ounces
Then we rewrite the sack weights:
14 pounds 9 ounces = 14 9/16
9 pounds 14 ounces = 9 14/16 = 9 7/8
Then, we subtract both values:
(14 9/16) - (9 7/8) = 4.6875 = 4 + 0.6875
Rewriting:
4 + 0.6875 = 4 + 6875/1000
4 + 1375/200 = 4 + 275/40
4 + 275/40 = 4 + 55/8
Answer:
the weight of the potatoes wendy use for the potato salad is:
4 + 55/8 pounds
