Answer:
119.2
Step-by-step explanation:
Given the following :
Mean (m) = 100 years
Standard deviation (sd) = 15 years
closest to the age of a Galápagos Islands giant tortoise at the 90th percentile of the
distribution?
Obtain the Zscore for 90th percentile (0.90) on the z table = 1.28
Zscore = (X - mean) / standard deviation
1.28 = (X - 100) / 15
1.28 × 15 = X - 100
19.2 = X - 100
19.2 + 100 = X
X = 119.2
The two numbers are very near 7200 and 300. The sum of those is a good estimate of your sum:
... 7200 + 300 = 7500
_____
If you're taught methods of addition that include "make a ten" or "make a hundred", you know you can "borrow" a 1 from 7203 (making it 7202) and loan that 1 to 299 to make it 300. Now, you know your sum is exactly 7202+300 = 7502, with no estimation necessary.
5x-1=19
1st you add the one over to the 19 and you'll get 20
then you do 5x=20
divide the 5x over to the 20 and your final answer is 4.
Answer: 11.4%
Step-by-step explanation:
100% of your life is 57 years
?% will be 6.5 years?
this is a simple ratio problem:
57 --> 100%
6.5 ---> (6.5 x 100)/57 ≅ 11.4%
You have known the person for about 11.4% of your life.
