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
Answer:
20 Lizard lollies.
Step-by-step explanation:
There are 10 lizard lollis. This is out of 10+4+6 = 20 total treats. This makes the probability of drawing a lizard lollis 10/20 = 1/2.
This means out of 40 treats handed out, we can expect him to give out 1/2(40) = 20 lizard lollis.
Answer:
The solution is given below:
Step-by-step explanation:
The computation is shown below:
= 19 + 7 divided by 2 - 5
= (19 + 7) ÷ (2) - 5
= 26 ÷ 2 - 5
= 13 - 5
= 8
Hence, after solving this the value would be 8
Therefore it is equal to the 8
Hence, the given statement is true
Answer:
The term "El Nino" refers to the warming of the central and eastern tropical Pacific waters that occurs every 3 to 7 years and typically lasts from 9 to 12 months. The 1997-1998 El Nino, the strongest ever recorded, affected climate patterns worldwide. Its effect, combined with an increasing trend in annual global temperatures, made 1998 the warmest year in the 20th century. Suppose you are a climatologist. You conduct a hypothesis test to determine whether the global mean temperature in the current year is different from the global mean temperature in 1998. Assume that the global mean temperature in 1998 is 14.3 degrees Celsius. You obtain a preliminary sample of temperatures from recording stations worldwide, which yields a sample mean of x bar = 15.1 degrees Celsius. Let mu denote the global mean temperature in the current year. Formulate your null and alternative hypotheses by selecting the appropriate values in the blue drop-down menus that follow.
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Answer:
Step A. 3(m - 2) + 2(m - 2) and 5(m - 2) are equivalent expressions.
Step-by-step explanation:
Step B. If you calculate 3(m - 2) + 2(m - 2) you will see it will equal to 5(m - 2) therefore, they are equal.
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