1.5 metres is the length of the tape. Hope this helps :)
A significant figure is every symbol that made the number itself.
In this case, the number 40.00 has four figures but only two of them are significant 40, this is because you haven't got any more decimals than the first zero.
If you have a case with zeros in front, you take to the first non zero digits.
For example, 0.071004 you wold express as 0.071 and those 7, and 1 are the significant ones.
Density of a substance is defined as the mass of the substance divided by the volume.
Density of the substance= 0.242 g cm⁻³
volume of the substance= 2.50 in³
As, 1 in³= 16.39 cm³
So, 2.50 in³= 16.39× 2.50 cm³=40.97 cm³
As ,
Mass=volume ×Density
Mass=40.97 × 0.242
Mass=9.916 g.