A student wrote 3 hours 3 minutes as 3.3 hours. By what percentage of an hour did he go wrong?
Answers
3hours 3minutes= 3+1/60 hrs (as 1hr=60 min) 3+1/60=3+1/20 =3.05 hrs. If student write it 3.3 hr then persentage he is right with is 3.05/3.3×100=92.42% And persentage he is wrong is 100-92.42=7.58%
Given:
3 hours 3 minutes is written as 3.3 hours.
Find:
Percentage of an hour by which he went wrong.
Answer:
He went wrong by 25 % of an hour.
Solution:
1 hour = 60 minutes
∴ 3 hours = (3 × 60) minutes
= 180 minutes
3 hours 3 minutes = 180 + 3 = 183 minutes
Now, we will convert minutes into hours in decimal form.
1 minute = 1/60 hours
183 minutes = 183/60 hours
= 3.05 hours
∴ Correct value of 3 hours 3 minutes, H₁ = 183 minutes = 3.05 hours
Incorrect value written by the student, H₂ = 3.3 hours
Percent of an hour by which he went wrong = Difference in values/1 hour × 100 %
Percent of an hour by which he went wrong = (H₂ - H₁)/1 × 100 %
= (3.3 - 3.05) × 100 %
= 0.25 × 100 %
= 25 %
Hence, he went wrong by 25 % of an hour.
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