It would be 4.05 ft

There is a rule of thumb in asphalt paving that says that one ton of asphalt (should say hot mix asphalt) will cover one square yard of area at a depth of 18 inches.

The rule further states that to find the area that can be covered by the same one ton at smaller depths, divide the depth you are laying at, into 18. The answer is the number of square yards the depth you are using will cover. For instance, at 9 inch depth one ton would cover 18/9=2 sy

So, in your case, divide 18 by 4 = 4.5 square yards per ton (or 40.5 sq ft)

Since you have a defined width of 10 feet, divide 40.5 sf by 10) = 4.05 ft length

The rule is based on a weight per cubic foot of about 149.7 lbs per cf. Weights of actual mixes can vary and will affect the yield or coverage.

But to check: 4.05 ft by 10 ft x 0.33 (4 inches in feet) = 13.365 cf

13.365 cf x 149.7 lbs/cf = 2,000.7 lbs

Instead of using the 18 inch block, you can just compute the volume of what is going to be covered, in cubic feet, times 148.7 lbs per cf and be in the ball park.

Then divide the weight of the total mix needed by 2000 for tons. But for total accuracy you need the mix design weight. Compaction is also a factor.

The rule further states that to find the area that can be covered by the same one ton at smaller depths, divide the depth you are laying at, into 18. The answer is the number of square yards the depth you are using will cover. For instance, at 9 inch depth one ton would cover 18/9=2 sy

So, in your case, divide 18 by 4 = 4.5 square yards per ton (or 40.5 sq ft)

Since you have a defined width of 10 feet, divide 40.5 sf by 10) = 4.05 ft length

The rule is based on a weight per cubic foot of about 149.7 lbs per cf. Weights of actual mixes can vary and will affect the yield or coverage.

But to check: 4.05 ft by 10 ft x 0.33 (4 inches in feet) = 13.365 cf

13.365 cf x 149.7 lbs/cf = 2,000.7 lbs

Instead of using the 18 inch block, you can just compute the volume of what is going to be covered, in cubic feet, times 148.7 lbs per cf and be in the ball park.

Then divide the weight of the total mix needed by 2000 for tons. But for total accuracy you need the mix design weight. Compaction is also a factor.