See explanation below.
Work Step by Step
The scale markings are 0.2 cm apart. The end of the metal strip falls between the mark for 7.4 cm and 7.6 cm. If we assume that one can divide the space between markings into fourths, the uncertainty is one-fourth the separation between the marks. Therefore, since the end of the metal strip falls between 7.45 and 7.55 we can report its length as 7.50 ± 0.05 cm. If the assumption is that one can divide the space between markings into halves, only then the result is 7.5 ±0.1 cm.