Question

A diver was collecting water samples from a lake. He collected a sample at every interval of 3 m,
starting at 5 m below the water surface. The final sample was
collected at a depth of 35 m. How many samples did he collect?​

(note: answers with steps only will be approved)​

Answer 1

Here,
a=5 (distance at which first sample is collected/the first term)

an= 35 (distance at which last sample is collected/last term)

d= secound term - first term
=8-5=3 (interval at which sample is collected)

n= no of samples collected,which is what we need to find
Substitute all the values in the formula

We get,
an=a+(n-1) × d

35=5+(n-1) × 3
30=(n-1)×3
30=3n-3
33=3n
n = 11