Thinking about the units of a problem can often help you devise a strategy for solving it. Consider the types of units that go with the following equations, then decide which equations are valid statements. View Available Hint(s) Hint 1. How to think about the units (click to open) time = distance speed ? dis tance = speed x time eed ? distance= Time speed - distance x time ? speed= distance time

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Ans A

As the formula for speed = distance/time the correct answers here will be –

Time = distance/speed

Distance = Speed x Time

(e) Speed = distance/time

Ans B

The correct option is (D) since the lifetime of sun is 10.8 billion years. Thus, the time shown by you is very short.

As you have provided the units which is second here for time, option a, c and e are incorrect

Ans C

Density = Mass/Volume

As the slab is in cuboid shape, volume will be length x breadth x height

Thus, Mass = density x volume

Volume = 100 cm x 300 cm x 4 cm

2.75 x 100 x 300 x 4

The correct option is (E)

Option (b) is incorrect because unit for density is incorrect

Option a is incorrect due to incorrect formula. Thus option € is correct where the metre values are first converted into centimetre and proper formula is used.