You have to cancel out the variables and then you plug it into a calculator.
Its 7 because of the queetiom of the answer and decimal
Answer:

Step-by-step explanation:
From the question we are told that:
Exponential distribution mean 
Distance 
Generally the equation for Exponential distribution is mathematically given by


Therefore
Possion Y


Generally the equation for The probability that there are no major cracks in a 10 mile stretch of the highway is mathematically given by



For this case we have the following quadratic equation:

This is equivalent to:

Where:

The discriminant is given by:

Substituting the values we have:

The discriminant is zero, so the equation has two equal real roots.
Answer:
The equation has two equal real roots.