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Finding the Fourth Proportional to 840.78, 1,256.18 and 812.07

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Solution

The fourth proportional to 840.78, 1,256.18 and 812.07 is: 1,213.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.78 : 1,256.18 = 812.07 : x
  2. Step 2: Convert to fraction form
    840.78/1,256.18 = 812.07/x
  3. Step 3: Cross multiply
    840.78x = 1,256.18 × 812.07
  4. Step 4: Simplify right side
    840.78x = 1,020,106.09
  5. Step 5: Solve for x
    x = 1,020,106.09/840.78
  6. Step 6: Final answer
    x = 1,213.29

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.