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

Hi,
From this question
a=5
d=3
a n =35
so the formula is an=a+(n-1)d
35=5+(n-1)3
n=(35-5)/3
10
so the 10th samples.

Regards

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If he starts at 5m and finishes at 35m. So, he travelled a distance of 30m. It means the driver collected 10 samples.
Solution
Starting point- 5m
​Finishing point- 35m
​So now we subtract the starting point from the finishing point which is 30m. Now you can easily find the samples he found. And he found 10 samples.

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35 samples

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10
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