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If 0 lt x lt 1000 and [(x)/(2)] +[(x)/(3...

If `0 lt x lt 1000 and [(x)/(2)] +[(x)/(3)]+[(x)/(5)] =(31)/(30)x`, where [x] is the greatest integer less than or equal to x, the number of possible values of x is

A

34

B

32

C

33

D

None of these

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The correct Answer is:
To solve the equation given in the question, we will follow these steps: ### Step 1: Understand the equation The equation we have is: \[ \left\lfloor \frac{x}{2} \right\rfloor + \left\lfloor \frac{x}{3} \right\rfloor + \left\lfloor \frac{x}{5} \right\rfloor = \frac{31}{30} x \] where \(\left\lfloor x \right\rfloor\) denotes the greatest integer less than or equal to \(x\). ### Step 2: Determine the conditions for \(x\) Given that \(0 < x < 1000\), we need to ensure that the right-hand side of the equation is an integer. For \(\frac{31}{30} x\) to be an integer, \(x\) must be a multiple of 30. Thus, we can express \(x\) as: \[ x = 30p \] where \(p\) is an integer. ### Step 3: Substitute \(x\) in the equation Now substituting \(x = 30p\) into the left-hand side of the equation: \[ \left\lfloor \frac{30p}{2} \right\rfloor + \left\lfloor \frac{30p}{3} \right\rfloor + \left\lfloor \frac{30p}{5} \right\rfloor \] Calculating each term: \[ \left\lfloor \frac{30p}{2} \right\rfloor = \left\lfloor 15p \right\rfloor = 15p \] \[ \left\lfloor \frac{30p}{3} \right\rfloor = \left\lfloor 10p \right\rfloor = 10p \] \[ \left\lfloor \frac{30p}{5} \right\rfloor = \left\lfloor 6p \right\rfloor = 6p \] Adding these together gives: \[ 15p + 10p + 6p = 31p \] ### Step 4: Set the left-hand side equal to the right-hand side Now we set the left-hand side equal to the right-hand side: \[ 31p = \frac{31}{30} (30p) \] This simplifies to: \[ 31p = 31p \] This equality holds for all \(p\), confirming that our substitution is valid. ### Step 5: Determine the range for \(p\) Since \(0 < x < 1000\), substituting \(x = 30p\) gives: \[ 0 < 30p < 1000 \] Dividing the entire inequality by 30: \[ 0 < p < \frac{1000}{30} \approx 33.33 \] Thus, \(p\) can take integer values from 1 to 33 (inclusive). ### Step 6: Count the possible values of \(p\) The possible integer values for \(p\) are: \[ 1, 2, 3, \ldots, 33 \] This gives us a total of 33 possible values for \(p\). ### Final Answer Thus, the number of possible values of \(x\) is: \[ \boxed{33} \]
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