Answer
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Hint: Here we will simply use the unitary method to get the desired answer i.e. we will first evaluate the time taken to weave 1 m of cloth and then we will find the time taken to weave 25 m of cloth by multiplying.
Complete step by step answer:
It is given that industrial loom weaves 0.128 meters of cloth every second.
This implies, the industrial loom weaves 1-meter cloth in \[\dfrac{1}{{0.128}}\]sec.
Now we have to find the time taken to weave 25 m of cloth.
Hence we have to multiply the time taken to weave 1-meter cloth to 25 to get the desired time taken.
Hence on multiplying we get:-
\[\Rightarrow {\text{Time taken to weave 25 m of cloth}} = \dfrac{1}{{0.128}} \times 25\]
Converting the decimals into fractions we get:-
\[\Rightarrow {\text{Time taken to weave 25 m of cloth}} = \dfrac{{1000}}{{128}} \times 25\]
Multiplying the terms we get:-
\[\Rightarrow {\text{Time taken to weave 25 m of cloth}} = \dfrac{{19531}}{{100}}\]
Now again converting the fraction back into decimal we get:-
\[\Rightarrow {\text{Time taken to weave 25 m of cloth}} = 195.31 \approx 195\sec \]
Therefore, 195 seconds are needed to weave 25 meters of cloth.
Therefore, option (B) is the correct option.
Note:
Students should note that when a number is divided by any power of 10 then the decimal point of the number gets shifted to the left by the number of decimal points equal to the power of 10 and when a number is multiplied by any power of 10 then the decimal point of the number gets shifted to the right by the number of decimal points equal to the power of 10.
Also, students should note that when we have to evaluate the value for larger quantities then we have to use multiplication and when we have to evaluate the value for smaller quantities then we have to use division.
Complete step by step answer:
It is given that industrial loom weaves 0.128 meters of cloth every second.
This implies, the industrial loom weaves 1-meter cloth in \[\dfrac{1}{{0.128}}\]sec.
Now we have to find the time taken to weave 25 m of cloth.
Hence we have to multiply the time taken to weave 1-meter cloth to 25 to get the desired time taken.
Hence on multiplying we get:-
\[\Rightarrow {\text{Time taken to weave 25 m of cloth}} = \dfrac{1}{{0.128}} \times 25\]
Converting the decimals into fractions we get:-
\[\Rightarrow {\text{Time taken to weave 25 m of cloth}} = \dfrac{{1000}}{{128}} \times 25\]
Multiplying the terms we get:-
\[\Rightarrow {\text{Time taken to weave 25 m of cloth}} = \dfrac{{19531}}{{100}}\]
Now again converting the fraction back into decimal we get:-
\[\Rightarrow {\text{Time taken to weave 25 m of cloth}} = 195.31 \approx 195\sec \]
Therefore, 195 seconds are needed to weave 25 meters of cloth.
Therefore, option (B) is the correct option.
Note:
Students should note that when a number is divided by any power of 10 then the decimal point of the number gets shifted to the left by the number of decimal points equal to the power of 10 and when a number is multiplied by any power of 10 then the decimal point of the number gets shifted to the right by the number of decimal points equal to the power of 10.
Also, students should note that when we have to evaluate the value for larger quantities then we have to use multiplication and when we have to evaluate the value for smaller quantities then we have to use division.