Question
The table shows how the cost of a tractor repair depends on the time needed for the repair.
TRACTOR REPAIR COSTS
Repair Time
(hours)
Cost
(dollars)
2 180
5 450
? 630
10 900
20 1,800
Which expression can be used to find the number that is missing from the third row of the table?
TRACTOR REPAIR COSTS
Repair Time
(hours)
Cost
(dollars)
2 180
5 450
? 630
10 900
20 1,800
Which expression can be used to find the number that is missing from the third row of the table?
Answers
GPT-4o mini
To find the missing repair time corresponding to the cost of $630, we first observe the relationship between the repair time and cost in the table.
From the table, we can see:
- For 2 hours, the cost is $180.
- For 5 hours, the cost is $450.
- For 10 hours, the cost is $900.
- For 20 hours, the cost is $1,800.
Now we can look for a consistent pattern. Let's calculate the cost per hour for the known values:
- For 2 hours:
\[
\frac{180}{2} = 90 \text{ dollars per hour}
\]
- For 5 hours:
\[
\frac{450}{5} = 90 \text{ dollars per hour}
\]
- For 10 hours:
\[
\frac{900}{10} = 90 \text{ dollars per hour}
\]
- For 20 hours:
\[
\frac{1800}{20} = 90 \text{ dollars per hour}
\]
The cost appears to increase linearly at a rate of $90 per hour.
Since we are looking for the repair time corresponding to a cost of $630, we can set up the following equation based on the cost per hour:
\[
\text{Cost} = \text{Repair Time (hours)} \times 90
\]
Substituting the cost of $630 into the equation:
\[
630 = \text{Repair Time} \times 90
\]
Now we can solve for the repair time:
\[
\text{Repair Time} = \frac{630}{90}
\]
Calculating that gives us:
\[
\text{Repair Time} = 7
\]
Thus, the missing number in the third row of the table is 7 hours.
Therefore, the expression that can be used to find the missing number is:
\[
\text{Repair Time} = \frac{630}{90}
\]
From the table, we can see:
- For 2 hours, the cost is $180.
- For 5 hours, the cost is $450.
- For 10 hours, the cost is $900.
- For 20 hours, the cost is $1,800.
Now we can look for a consistent pattern. Let's calculate the cost per hour for the known values:
- For 2 hours:
\[
\frac{180}{2} = 90 \text{ dollars per hour}
\]
- For 5 hours:
\[
\frac{450}{5} = 90 \text{ dollars per hour}
\]
- For 10 hours:
\[
\frac{900}{10} = 90 \text{ dollars per hour}
\]
- For 20 hours:
\[
\frac{1800}{20} = 90 \text{ dollars per hour}
\]
The cost appears to increase linearly at a rate of $90 per hour.
Since we are looking for the repair time corresponding to a cost of $630, we can set up the following equation based on the cost per hour:
\[
\text{Cost} = \text{Repair Time (hours)} \times 90
\]
Substituting the cost of $630 into the equation:
\[
630 = \text{Repair Time} \times 90
\]
Now we can solve for the repair time:
\[
\text{Repair Time} = \frac{630}{90}
\]
Calculating that gives us:
\[
\text{Repair Time} = 7
\]
Thus, the missing number in the third row of the table is 7 hours.
Therefore, the expression that can be used to find the missing number is:
\[
\text{Repair Time} = \frac{630}{90}
\]