2. A 4 × 12 built-up girder is 30″. How many board feet does this girder contain? (Round your answer to the nearest whole number.)
A. 107
B. 312
C. 128
D. 96
I think the answer is C.128.
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3. Calculate the number of hours needed to frame a one-story house 36′ long, in which 2 × 6 × 16 joists will be placed 16″ OC. (Round your answer to the nearest whole number.)
A. 4
B. 5
C. 7
D. 6
I think it's B. 5 hours.
2. Correct! The answer for the number of board feet in the girder is C. 128.
3. Correct! The answer for the number of hours needed to frame the house is B. 5 hours.
For question 2, to calculate the number of board feet in the girder, we need to find the volume by multiplying the dimensions together.
The dimensions of the girder are 4 inches in width, 12 inches in depth, and 30 inches in length.
To convert the dimensions to feet, we divide each dimension by 12:
4 inches = 4/12 feet = 1/3 feet
12 inches = 12/12 feet = 1 foot
30 inches = 30/12 feet = 2.5 feet
Now, we multiply the dimensions together to find the volume in board feet:
1/3 feet * 1 foot * 2.5 feet = 0.8333 cubic feet
Since board feet is a unit of volume measurement, we don't need to round to the nearest whole number.
Therefore, the correct answer for question 2 is not C. 128.
Now, moving on to question 3, to calculate the number of hours needed to frame a one-story house, we need to determine how many joists are required and then calculate the time needed for each joist.
The house is 36 feet long and the joists are placed 16 inches on center (OC).
First, we convert the joist spacing to feet:
16 inches = 16/12 feet = 1.3333 feet
Next, we determine the number of joists required by dividing the length of the house by the joist spacing:
36 feet / 1.3333 feet = 27 joists
Finally, we calculate the time needed to frame each joist.
Assuming it takes approximately 20 minutes (1/3 of an hour) to frame a joist, we multiply the number of joists by the time per joist:
27 joists * 1/3 hour = 9 hours
Therefore, the correct answer for question 3 is not B. 5 hours.
I apologize for the incorrect answers. The correct answers are:
2. The girder contains approximately 1 board foot. None of the provided answer options are correct.
3. The number of hours needed to frame the one-story house is 9 hours. None of the provided answer options are correct.
To calculate the number of board feet in a built-up girder, you need to multiply the dimensions of the girder and then divide by 12.
In this case, the girder is 4 inches thick and 12 inches wide, with a length of 30 inches.
The formula to calculate board feet is: board feet = (thickness x width x length) / 12.
Plugging in the values: board feet = (4 x 12 x 30) / 12 = 480 / 12 = 40 board feet.
Therefore, the correct answer is not C.128, but instead there seems to be an error. None of the options given match the correct answer of 40 board feet.
Moving on to the second question,
To calculate the number of hours needed to frame a one-story house, you need to consider the length of the house and the spacing of the joists.
In this case, the house is 36 feet long, and the joists are 2 inches thick, 6 inches wide, and spaced 16 inches on center.
First, we need to convert the length of the house to inches: 36 feet x 12 inches/foot = 432 inches.
Next, we need to calculate the number of spaces between the joists, which is the length of the house divided by the spacing between the joists: 432 inches / 16 inches = 27 spaces.
The total number of joists needed is equal to the number of spaces + 1, because there is one joist at the beginning and end of the house: 27 spaces + 1 = 28 joists.
Finally, considering that each joist takes 16 inches of time to install, we can calculate the total time needed to frame the house: 28 joists x 16 inches = 448 inches.
Since the question asks for the number of hours, we divide the total inches by 12 to get the number of feet, and then divide by 16 to get the number of hours: 448 inches / 12 / 16 = 3.5 hours.
Round to the nearest whole number, the correct answer is not B. 5 hours, but rather A. 4 hours.
It's important to carefully check your calculations and ensure that the answers match the given options.