Using a builder's level, the grade for a footing is being set. The bottom of the footing will be at an elevation of 94.00. A back sight to the bench mark (elevation of 100.00) has a rod reading of 4.70. If the grade is correct, the rod reading for the bottom of the footing should be:

Using a builder's level, the grade for a footing is being set. The bottom of the footing will be at an elevation of 94.00. A back sight to the bench mark (elevation of 100.00) has a rod reading of 4.70. If the grade is correct, the rod reading for the bottom of the footing should be:

• A. 6.30 feet
• B. 10.70 feet
• C. 4.70 feet
• D. 94.00 feet

Answer: (B)

To determine the correct rod reading for the bottom of the footing, we first need to understand the relationship between benchmark elevation, back sight reading, and the intended footing elevation. The benchmark is at an elevation of 100.00 feet. When a back sight is taken, the rod reading indicates how far the instrument is above the point being measured. In this case, with a back sight reading of 4.70 feet, we can calculate the height of the instrument above the benchmark: Height of the instrument = Benchmark elevation - Rod reading Height of the instrument = 100.00 - 4.70 = 95.30 feet Now, we need to find the rod reading for the bottom of the footing, which we know will be at an elevation of 94.00 feet. We again use the height of the instrument to determine this: Rod reading for the bottom of the footing = Height of the instrument - Elevation of the footing Rod reading for the bottom of the footing = 95.30 - 94.00 = 1.30 feet However, this is not directly one of our options; instead, we need to interpret our findings in line with total elevation references. When reading the elevation through a

To determine the correct rod reading for the bottom of the footing, we first need to understand the relationship between benchmark elevation, back sight reading, and the intended footing elevation.

The benchmark is at an elevation of 100.00 feet. When a back sight is taken, the rod reading indicates how far the instrument is above the point being measured. In this case, with a back sight reading of 4.70 feet, we can calculate the height of the instrument above the benchmark:

Height of the instrument = Benchmark elevation - Rod reading

Height of the instrument = 100.00 - 4.70 = 95.30 feet

Now, we need to find the rod reading for the bottom of the footing, which we know will be at an elevation of 94.00 feet. We again use the height of the instrument to determine this:

Rod reading for the bottom of the footing = Height of the instrument - Elevation of the footing

Rod reading for the bottom of the footing = 95.30 - 94.00 = 1.30 feet

However, this is not directly one of our options; instead, we need to interpret our findings in line with total elevation references.

When reading the elevation through a