The possible answers are 15,5 and 10,10
Answer:
The answers is "
Option B".
Step-by-step explanation:

Where,
predicted value of lead content when traffic flow is 15.


Calculating thet-critical value
The lower predicted value 

When
of CI use as the expected lead content:

Answer:
22 hours (B)
Step-by-step explanation:
John's velocity = 55mph
Sally's velocity = 65mph
John's time taken = x
Sally's time taken = x - 4
since they must cover the same distance.
and, distance = vel × time
Sally's vel × time = John's vel × time
55x = 65(x-4)
55x = 65x - 220
-10x = -220
x = 22 hours.
Therefore, Sally catches up after 22 hours