The following results were obtained for the concentration of nitrite ions in a sample of river

water:

Experiment

1

Nitrite lons

(mg/)

0.403

2

3

4

0410

0.401

0.380

Showing clearly ALL of your workings:

(6 marks)

0) Calculate the standard deviation of these analyses

00 Find the 95% and 99% confidence interval for the mean nitrite on concentration.

(marks)

The value for Experiment 4 (0.380) was questionable and was subsequently