Linear Inequalities

In drilling world’s deepest hole it was found that the temperature T in degree Celsius, x km below the earth’s surface was given by T = 30 + 25 (x – 3), 3 ≤ x ≤ 15. At what depth will the temperature be between 155°C and 205°C?

\[T\text{ }=\text{ }30\text{ }+\text{ }25\left( x\text{ }\text{ }3 \right),\text{ }3\text{ }\le \text{ }x\text{ }\le \text{ }15;\] where, T = temperature and x = depth inside the earth The...

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A solution of 9% acid is to be diluted by adding 3% acid solution to it. The resulting mixture is to be more than 5% but less than 7% acid. If there is 460 litres of the 9% solution, how many litres of 3% solution will have to be added?

According to the question, Let x litres of 3% solution is to be added to 460 liters of the 9% of solution Then, we get, Total solution = \[\left( 460\text{ }+\text{ }x \right)\text{ }litres\] Total...

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The water acidity in a pool is considered normal when the average pH reading of three daily measurements is between 8.2 and 8.5. If the first two pH readings are 8.48 and 8.35, find the range of pH value for the third reading that will result in the acidity level being normal.

According to the question, First reading = 8.48 Second reading = 8.35 Now, let the third reading be ‘x’ Average pH should be between 8.2 and 8.5 Average \[pH~=\text{ }\left( 8.48\text{ }+\text{...

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A man wants to cut three lengths from a single piece of board of length \[91\]cm. The second length is to be \[3\]cm longer than the shortest and the third length is to be twice as long as the shortest. What are the possible lengths of the shortest board if the third piece is to be at least \[5\]cm longer than the second?

Solution: Let us consider the length of the shortest piece be x cm From the question, length of the second piece = \[(x+3)\]cm Given, length of third piece is to be twice as long as the shortest =...

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To receive Grade ‘A’ in a course, one must obtain an average of \[90\] marks or more in five examinations (each of \[100\] marks). If Sunita’s marks in first four examinations are \[87,92,94\] and \[95\], find minimum marks that Sunita must obtain in fifth examination to get grade ‘A’ in the course.

Solution: Let us consider Sunita scored x marks in her fifth examination From the given question  in order to receive A grade in the course she must have to obtain average \[90\] marks or more in...

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