Sampling distribution - Probability that exactly 6 cars go atleast 7 years but less than 10 years

I am attempting to solve a satistics and probability sum.

It states that mean time before failure for a car is 8 years with standard deviation of 1 year. If 10 cars are sampled; then what is Probability that exactly 6 cars go at least 7 years before failure but less than 10 years.

how to solve such problems?