Answer:
b) 47ml
Explanation:
The beaker would look like this:
60 mL
50 mL
------- The bottom of the meniscus is here
40 mL
30 mL
So we have between 40 and 50 mL. There are 10 mL of "distance" between those two values, and three fourths of that difference is (10 * 3/4) 7.5 mL.
So the volume is 47.5 mL, but because the measurement instrument (the beaker) does not handle decimals, the value we should report is 47 mL.