Step-by-step explanation:
Initially, there's only 1 letter.
Tania sends the letter to 4 friends.
Each friend sends a letter to 4 more friends (4 × 4 = 16).
Each of those friends sends to 4 more friends (16 × 4 = 64).
The pattern is 1, 4, 16, 64, etc.
This is a geometric sequence. The first term is 1 and each term is 4 times the previous term.
a₁ = 1
aₙ = 4 aₙ₋₁
The explicit formula is:
aₙ = 1 (4)ⁿ⁻¹
We’ll subtract the exponent in the denominator from the exponent in the numerator, keeping the base the same. Cant be simplified, because the base of the expression in the numerator is y and the base of the expression in the denominator is x.
Answer:
78.88%
Step-by-step explanation:
We have been given that
The z-score formula is given by
For 
For 
Now, we find the corresponding probability from the standard z score table.
For the z score -1.25, we have the probability 0.1056
For the z score 1.25, we have the probability 0.8944
Therefore, the percent of the trees that are between 20 and 30 years old is given by
0.8944 - 0.1056
= 0.7888
=78.88%
