Answer:
a) 1450watts
b) 564watts
c) 1.11
Explanation:
Power consumed = IV
I is the current rating
V is the operating voltage
If a blow-dryer and a vacuum cleaner each operate with a voltage of 120 V and the current rating of the blow-dryer is 12 A, while that of the vacuum cleaner is 4.7 A then their individual power rating is calculated thus;
a) For blow-dryer
Operating voltage = 120V
Its current rating = 12A
Power consumed = IV
= 120×12
= 1440watts
b) For vacuum cleaner:
Operating voltage is the same as that of blow dryer = 120V
Its current rating = 4.7A
Power consumed = IV
= 120×4.7
= 564watts
c) Energy used = Power consumed × time taken
Energy used = Power × time
Energy used by blow dryer = 1440×20×60
= 1,728,000Joules
Energy used up by vacuum cleaner = 564×46×60
= 564×2760
= 1,556,640Joules
Ratio of the energy used by the blow-dryer in 20 minutes to the energy used by the vacuum cleaner in 46 minutes will be 1,728,000/1,556,640 = 1.11
Explanation:
When Joe works alone, the total number of words he typed can be given by:
Total words = (40 words per minute) x (60 minutes per hour) x (2.5 hours)
Total words = 6000 words
Now, when Joe and Mark work together, let 'y' be the number of hours for which they both work simultaneously:
Total words = Words Typed by Joe + Words Typed by Mark
6000 = {(40 words per minute) x (60 minutes per hours) x (y hours)} + {(20 words per minute) x (60 minutes per hours) x (y hours)}
6000 = 2400y + 1200y = 3600y
y = 1.67 hours = 1 hour and 40 minutes
Thus, working together simultaneously, Joe and Mark will take 1 hour and 40 minutes to complete the report.
