Home / 812.70-1,121.16-638.55

Finding the Fourth Proportional to 812.70, 1,121.16 and 638.55

Calculator

Solution

The fourth proportional to 812.70, 1,121.16 and 638.55 is: 880.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.70 : 1,121.16 = 638.55 : x
  2. Step 2: Convert to fraction form
    812.70/1,121.16 = 638.55/x
  3. Step 3: Cross multiply
    812.70x = 1,121.16 × 638.55
  4. Step 4: Simplify right side
    812.70x = 715,916.72
  5. Step 5: Solve for x
    x = 715,916.72/812.70
  6. Step 6: Final answer
    x = 880.91

Related Problems

Find fourth proportional to 406.35, 560.58 and 319.28
Half scale
Find fourth proportional to 1,625.40, 2,242.32 and 1,277.10
Double scale
Find fourth proportional to 813.70, 1,122.54 and 639.55
Similar ratio
Find fourth proportional to 1,219.05, 1,681.74 and 957.83
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.