Home / 621.20-931.32-312.90

Finding the Fourth Proportional to 621.20, 931.32 and 312.90

Calculator

Solution

The fourth proportional to 621.20, 931.32 and 312.90 is: 469.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    621.20 : 931.32 = 312.90 : x
  2. Step 2: Convert to fraction form
    621.20/931.32 = 312.90/x
  3. Step 3: Cross multiply
    621.20x = 931.32 × 312.90
  4. Step 4: Simplify right side
    621.20x = 291,410.03
  5. Step 5: Solve for x
    x = 291,410.03/621.20
  6. Step 6: Final answer
    x = 469.11

Related Problems

Find fourth proportional to 310.60, 465.66 and 156.45
Half scale
Find fourth proportional to 1,242.39, 1,862.64 and 625.80
Double scale
Find fourth proportional to 622.20, 932.82 and 313.90
Similar ratio
Find fourth proportional to 931.79, 1,396.98 and 469.35
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.