How many cubic yards of concrete will be needed to replace a section of sidewalk 150ft long, 5ft wide and 4 inches thick

4 inches = 1/3 foot

So the volume of that section is (150ft x 5ft x 1/3 ft) = 250 cubic feet

The whole trick to this question is knowing

how many cubic feet make 1 cubic yard.

1 yard = 3 ft

(1yd x 1 yd x 1yd) = 1 yd³

(3ft x 3ft x 3ft) = (3 ft) ³ = (3) ³ x (ft) ³ = 27 ft³ <===

For the sidewalk project,

250 ft³ = (250 / 27) = 9.26 yard³.

I think the way concrete contractors operate, they'll

want you to order and pay for 10 cubic yards.