The sample which is likely to produce the most valid result is Richard's sample because there was no statistical bias. Statistical bias is the systematic favoritism of certain individuals in the study. Just like what Adriana, Henry and Malik did in conducting their surveys, they choose people who are point of interest and also who are near them. In the way Richard conducted his survey, he used a random sampling technique, this is a method of selecting a sample from a population in such a way that every possible individual can be chosen and he doesn't know who these people are.
Cost of company A=monthlyfee+text=20+0.03t where t=number of texts
A=20+0.03t
company b is monthlyfee+texts=5+0.07t
B=5+0.07t
1.
c=20+0.03t
c=5+0.07t
using c for cost is confusing because we can't tell which is for which company
2.
equal, means the costs are equal so
20+0.03t=5+0.07t
minus 5 from both sides
15+0.03t=0.07t
minus 0.03t from both sides
15=0.04t
divide both sides by 0.04
375=t
the answer is 375 texts
Answer:
I don't really know but I will help you if I can
This is a geometric sequence with first term 1 and common ratio -1/2. r=-1/2.
a(n) = a(1)*(r)^(n-1).
Check: If n=2 our formula must return -1/2. Does it?
a(2) = 1(-1/2)^(2-1) = (-1/2)^1 = - 1/2. Yes.
a(3) should be 1/4. Is it? a(3) = (-1/2)^(3-1) = 1/4 Yes.
Then a(8) = (-1/2)^(8-1) = (-1/2)^7 = -1 / 2^7 = -1/128 (answer)
