A750 watt hairdryer is used for 15 minutes. calculate the kwhr used. calculate the cost to use 15 min. every day for 1 year @ 8 cents/kwhr

Part (a):
We know that:
1 kw = 1000 watt > Therefore, to convert watt into kw, we will divide by 1000
1 hour = 60 min > Therefore, to convert mins into hours, we will divide by 60
Based on the above, the conversion results for the two units together would be as follows:
1 watt minute is equivalent to 0.000017 kilowatt hours
Now, for the given , we will simply use cross multiplication to do the conversion as follows:
1 watt minute> 0.000017 kilowatt hours
750*15 > ??
750*15 watt min = 0.19125 kilowatt hour

Part (b):
From part a, we have that the consumption is 0.19125 kilowatt hour per day. Assuming that the year is 365 days, we would have:
yearly consumption = 0.19125 * 365 = 69.80625 kilowatt hour
The cost is 8 cents/kilowatt hour
Therefore:
yearly cost = 69.80625 * 8 = 558.45 cents

Hope this helps :)