Bob does 2/7 of a book in 1 hour.how long will he take to do the remaining work?
To find the amount of work remaining, subtract the work already done from the total work.
Let's say the total work in the book is represented by "W".
Bob has done 2/7 of the work in 1 hour, which is 2/7 * W = (2W)/7.
The remaining work can be found by subtracting the work already done from the total work: W - (2W)/7.
To find the time it will take Bob to do the remaining work, we need to establish a ratio.
Bob does (2W)/7 work in 1 hour, so the ratio is (2W)/7 : 1 hour.
To find how long it will take Bob to do the remaining work, we can use the cross-multiplication method.
((2W)/7) / (1 hour) = (W - (2W)/7) / (x hours).
Where x is the time it will take Bob to do the remaining work.
Simplifying the equation:
((2W)/7) / (1 hour) = (W - (2W)/7) / (x hours)
((2W)/7)*(x hours) = (W - (2W)/7)*(1 hour)
(2Wx)/7 = W - (2W)/7
Now, solving for x:
Multiply both sides by 7 to eliminate the denominators:
2Wx = 7W - 2W
2Wx = 5W
x = (5W)/(2W)
x = 5/2
x = 2.5
Therefore, it will take Bob 2.5 hours to do the remaining work in the book.
To find out how long Bob will take to do the remaining work, we need to first determine how much work is remaining.
Bob has done 2/7 of the book in 1 hour, which means there is 7/7 - 2/7 = 5/7 of the book remaining.
Now, we know that Bob does 2/7 of the book in 1 hour. So, to find out how long it will take him to do 5/7 of the book, we can set up a proportion:
(2/7) / 1 = (5/7) / x
Cross-multiplying, we get:
(2/7) * x = (5/7) * 1
Simplifying:
2x/7 = 5/7
To get x alone, we can multiply both sides of the equation by 7:
2x = 5
Dividing both sides by 2:
x = 5/2 = 2.5
Therefore, it will take Bob 2.5 hours (or 2 hours and 30 minutes) to complete the remaining work.
1/(2/7) = 7/2
So, there are 5/2 hours left to go.