A2= 1
a3=-3
a4=-7
the common difference is -4
Answer: it will take 2.5 hours for both people to meet after person B leaves.
Step-by-step explanation:
The distance between the house of person A and his cousin's house is 234 miles.
At the point where they meet, they would have travelled 234 miles.
Person A travelled at an average speed of 44 miles per hour.
Let t represent the time spent by Person A in travelling from his house to the point where they meet.
Distance = speed × time
Distance covered by person A would be
44 × t = 44t
One and half hours later, person B leaves his house to visit person A, travelling at an average speed of 62 miles per hour. This means that total time spent by person B in travelling to the point where they meet is (t - 0.5) hours. Distance covered would be
62(t - 0.5) = 62t - 31
Since the total distance covered is 234 miles, then
44t + 62t - 31 = 234
106t = 234 + 31 = 265
t = 265/106 = 2.5 hours
The probability any one system works is 0.99
So the probability of any one system failing is 1-0.99 = 0.01, so basically a 1% chance of failure for any one system
Multiply out the value 0.01 with itself four times
0.01*0.01*0.01*0.01 = 0.000 000 01
I'm using spaces to make the number more readable
So the probability of all four systems failing is 0.00000001
Subtract this value from 1 to get
1 - 0.00000001 = 0.99999999
The answer is 0.99999999 which is what we'd expect. The probability of at least one of the systems working is very very close to 1 (aka 100%)
