the cost of operating an appliance varies jointly as the number of watts drawn, the hours of the operation and the cost per kilowatt-hour. At P8.99 per kilowatt-hour, how much would it cost when a 70-watt desk fan operates for 2 hours?
c = kwhp
You do not give any way to evaluate k
c = 70*2*8.99 = 1258.6k
Now supply the constant of variation, k.
Solution:
suppose: cost of appliance (c), number of watts (w), hours (h) and cost per kilowatt hour (p)
Math sentence:
c = kwhp
substitute:
c = k (70)(2)(8.99)
c = (1)(1258.6)
c = 1256.6
Therefore the cost of operation is 1,256 pesos and 6 centavos
What is the answer of that
To calculate the cost of operating an appliance, which varies jointly as the number of watts drawn, the hours of operation, and the cost per kilowatt-hour, you can follow these steps:
1. Determine the combined variation equation: In this case, the cost of operating the appliance varies jointly with the number of watts drawn, the hours of operation, and the cost per kilowatt-hour. So, the equation can be written as:
Cost = k * Watts * Hours * Cost per kilowatt-hour,
where k is a constant.
2. Determine the constant k: Since we have the values for cost, watts, hours, and cost per kilowatt-hour, we can solve for k by substituting these values into the equation. Let's use the given information to calculate the constant k.
Cost = k * 70 watts * 2 hours * P8.99/kilowatt-hour.
3. Calculate the cost: Now that we have determined the value of k, we can calculate the cost by substituting the values into the equation.
Cost = k * 70 watts * 2 hours * P8.99/kilowatt-hour.
Simplifying the equation:
Cost = k * 70 * 2 * P8.99 = 140 * P8.99 * k,
where k is the constant.
Given P8.99 per kilowatt-hour, we can calculate the cost as follows:
Cost = 140 * P8.99.
To get the final answer, we multiply 140 by P8.99:
Cost = 140 * 8.99 = P1,258.60.
Therefore, it would cost P1,258.60 when a 70-watt desk fan operates for 2 hours, assuming the cost per kilowatt-hour is P8.99.