Answer:
Step-by-step explanation:
Given

Required
Make t the subject

Cross Multiply


Collect Like Terms

Factorize:

Make t the subject

Answer:
I would say the easiest answer for me is 875
Step-by-step explanation:
Answer:
It takes less time sending 5 letters the traditional way with a probability of 36.7%.
Step-by-step explanation:
First we must take into account that:
- The traditional method is distributed X ~ Poisson(L = 1)
- The new method is distributed X ~ Poisson(L = 5)

Where L is the intensity in which the events happen in a time unit and x is the number of events.
To solve the problem we must calculate the probability of events (to send 5 letters) in a unit of time for both methods, so:
- For the traditional method:

- For the new method:

According to this calculations we have a higher probability of sending 5 letters with the traditional method in a unit of time, that is 36.7%. Whereas sending 5 letters with the new method is less probable in a unit of time. In other words, we have more events per unit of time with the traditional method.
Answer:
7.35 years
Step-by-step explanation:
Given that :
mean = 8.4
standard deviation = 0.6
From the negative z tables, the corresponding data for 0.04 = -1.75
So, using the z-score formula:


-1.75 × 0.6 = x - 8.4
- 1.05 = x - 8.4
x = -1.05 + 8.4
x = 7.35 years
the shortest lifespan will last less than 7.35 years
∴ the longest 4% will have lifespans longer than x = 8.4 + 1.75(0.6)
= 9.45 years