Answer:
D
Step-by-step explanation:
When the population standard deviation is unknown while constructing the confidence interval then the estimate of standard deviation calculated from sample is used and due to this the new type of variability arise and then for conducting a confidence interval for mean the t-distribution is used. For calculating confidence interval for mean there are two sampling distributions z distribution and t distribution. When sample size is small and population standard deviation is unknown then t-distribution is used.
The present age of father is 86 years old and present age of son is 48 years old
<em><u>Solution:</u></em>
Given that, a father is now 38 years older than his son
Ten years ago he was twice as old as his son
Let "x" be the age of son now
Therefore, from given,
Father age now = 38 + age of son now
Father age now = 38 + x
<em><u>Ten years ago he was twice as old as his son</u></em>
Age of son ten years ago = age of son now - 10
Age of son ten years ago = x - 10
Age of father ten years ago = 38 + x - 10
Then we get,
Age of father ten years ago = twice the age of son ten years ago
38 + x - 10 = 2(x - 10)
28 + x = 2x - 20
2x - x = 28 + 20
x = 48
Thus son age now is 48 years old
Father age now = x + 38 = 48 + 38 = 86
Thus present age of father is 86 years old and present age of son is 48 years old
Subtract the 45 minutes they were eating from 1:45pm since that’s when they arrived. You now have 1:00pm, you now just need to find out how long it is from 10:20 am to 1:00pm. HINT: it’s 2h 40m
This is easy do you want me to explain it or give you a direct answer
