Final answer:
The size of the real object is 1.69 cm.
Step-by-step explanation:
The magnification factor of an optical device can be calculated by dividing the size of the image by the size of the real object. In this case, the magnification factor is given as 2.9 and the size of the image is 4.9 cm. To find the size of the real object, we can rearrange the formula as follows:
Magnification factor = Size of image / Size of real object
2.9 = 4.9 cm / Size of real object
Solving for the size of the real object, we can cross multiply and divide to get:
Size of real object = (4.9 cm) / (2.9)
Size of real object = 1.69 cm
Therefore, the size of the real object is 1.69 cm.