In the following questions, round the given data to one significant figure to estimate the value asked for :
Problem 1 :
Tracy delivers 405 papers on a paper round. She does this every week for a year. Estimate the number of papers delivered in the year.
Solution :
Tracy delivers 405 papers on a paper round.
1 year = 365 days
Every week = 365/7 days
= 52
405 has 3 significant figures.
It can be rounded to one significant figures as 400.
52 has 2 significant figures.
It is rounded to one significant figures is 50.
Total number of papers = 400 × 50
= 20,000
Problem 2 :
In the school dining hall there are 18 benches, each with 12 chairs.
Estimate the number of chairs in the dining hall.
Solution :
Number of benches = 18
Each with 12 chairs.
18 has 2 significant figures.
It can be rounded to one significant figures as 20.
12 has 2 significant figures.
It is rounded to one significant figure as 10.
= 20 × 10
= 200
So, 20 chairs in the dining hall.
Problem 3 :
It took me 11 hours to drive the 1057 km from Calgary to Vancouver. Estimate my average speed in kilometres per hour.
Solution :
Distance = 1057 km
Time = 11 hours
1057 km has 4 significant figures.
It is rounded to one significant figure as 1000.
11 has 2 significant figures.
It is rounded to one significant figure as 10.
Average speed = Total distance covered/Total time taken
= 1000/10
= 100 km per hour
Problem 4 :
In 2006, an average of 1071 flights were scheduled to arrive in or depart from Dubai each day. If they each carried an average of 84 people, estimate the number of passengers handled by Dubai International Airport each day.
Solution :
Average flights = 1071
Number of people = 84
1071 has 4 significant figures.
It is rounded to one significant figures as 1000.
84 has 2 significant figures.
It is rounded to one significant figures as 80.
= 1000 × 80
= 80,000
So, each day 80,000 passengers were handled by Dubai International Airport
Problem 5 :
Tim counted 42 jelly beans in the bottom layer of a jar. He thinks that there are 38 layers in the jar. Estimate the number of jelly beans in the jar.
Solution :
Tim counted number of jelly beans = 42
Number of layers = 38
42 has 2 significant figures.
It is rounded to one significant figures as 40.
38 has 2 significant figures.
It is rounded to one significant figures as 40.
= 40 × 40
= 1600
So, the number of jelly beans in the jar is 1600.
Problem 6 :
Sally earned ϵ404 per week for 7 months of the year. Estimate the total amount of money she earned.
Solution :
Sally earned the money = ϵ404
Month of the year = 7
1 month = 4 weak
7 month = 7 × 4
7 month = 28 week
404 has 3 significant figures.
It is rounded to one significant figures as 400.
28 has 2 significant figures.
It is rounded to one significant figures as 30.
Total amount = 400 × 30
= ϵ12,000
So, she earned the money is ϵ12,000.
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