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Finding the Fourth Proportional to 1,407.40, 2,111.10 and 639.40

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Solution

The fourth proportional to 1,407.40, 2,111.10 and 639.40 is: 959.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,407.40 : 2,111.10 = 639.40 : x
  2. Step 2: Convert to fraction form
    1,407.40/2,111.10 = 639.40/x
  3. Step 3: Cross multiply
    1,407.40x = 2,111.10 × 639.40
  4. Step 4: Simplify right side
    1,407.40x = 1,349,837.34
  5. Step 5: Solve for x
    x = 1,349,837.34/1,407.40
  6. Step 6: Final answer
    x = 959.10

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Double scale
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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.