The fineness modulus (FM) of an aggregate sample is calculated by summing the cumulative percentage weight retained on the sieves and dividing by 100. The formula is:
\[ {Fineness\ Modulus} = \frac{\sum {percentage\ cumulative\ weight\ retained}}{100} \]
We are given the cumulative percentages for each sieve size as follows:
Thus, the fineness modulus is calculated as:
\[ FM = \frac{30 + 65 + 80 + 100}{100} = 3.75 \]
Therefore, the fineness modulus of the sample is 3.75, which corresponds to option (A).
| Point | Staff Readings Back side | Staff Readings Fore side | Remarks |
|---|---|---|---|
| P | -2.050 | - | 200.000 |
| Q | 1.050 | 0.95 | Change Point |
| R | - | -1.655 | - |