A crawler hoe having a 2.5-cy bucket and whose cost per hour, including the wages to an operator, is $109 will excavate and load haul units under the stated conditions as - depth of excavation is 12 feet, angle of swing is 80 degrees, percent swell is 14 and efficiency factor is 55 min per hour. The maximum digging depth of the machine is 22 feet. Use load bucket time 6 sec; swing loaded time 6 sec; dump bucket time 4 sec and swing empty time 5 sec. Determine the cost per bank cubic yard for the material sand and gravel. Show all the calculations with all the required checking.

To calculate the cost per bank cubic yard for the material sand and gravel, we need to consider the following steps:

1. Calculate the bucket capacity in bank cubic yards (BCY):
Given bucket capacity = 2.5 cubic yards
Percent swell = 14%
Bucket capacity in BCY = bucket capacity / (1 + swell/100)
Bucket capacity in BCY = 2.5 / (1 + 14/100) = 2.19 BCY

2. Determine the bank cubic yards per load:
Given depth of excavation = 12 feet
Maximum digging depth of the machine = 22 feet
Bank cubic yards per foot = 1
Bank cubic yards per load = depth of excavation * 2 * bucket capacity in BCY
Bank cubic yards per load = 12 * 2 * 2.19 = 52.56 BCY

3. Calculate the cycle time in minutes:
Given load bucket time = 6 sec
Given swing loaded time = 6 sec
Given dump bucket time = 4 sec
Given swing empty time = 5 sec
Cycle time = (load bucket time + swing loaded time + dump bucket time + swing empty time) / 60
Cycle time = (6 + 6 + 4 + 5) / 60 = 0.2167 hours

4. Determine the production rate in bank cubic yards per hour:
Given efficiency factor = 55% = 0.55
Production rate = 60 / cycle time * efficiency factor
Production rate = 60 / 0.2167 * 0.55 = 151.29 BCY/hr

5. Calculate the operating cost per bank cubic yard:
Given cost per hour = 109Operating cost per bank cubic yard = cost per hour / production rateOperating cost per bank cubic yard = 109 / 151.29 = 0.72 per BCY

### Answer
The cost per bank cubic yard for the material sand and gravel is 0.72$ per BCY.