The frequency distribution of the compressive strength of 20 concrete cube specimens is given in the table
Q. The frequency distribution of the compressive strength of 20 concrete cube specimens is given in the table.
| f (MPa) | Number of specimens with compressive strength equal to f |
| 23 | 4 |
| 28 | 2 |
| 22.5 | 5 |
| 31 | 5 |
| 29 | 4 |
If 𝜇 is the mean strength of the specimens and 𝜎 is the standard deviation, the number of specimens (out of 20) with compressive strength less than 𝜇 − 3𝜎 is
Ans: 0
Sol:
Mean strength,
∴ Number of specimen with compressive strength less than 15.485 MPa are zero.