Home / 387.40-579.90-305.80

Finding the Fourth Proportional to 387.40, 579.90 and 305.80

Calculator

Solution

The fourth proportional to 387.40, 579.90 and 305.80 is: 457.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    387.40 : 579.90 = 305.80 : x
  2. Step 2: Convert to fraction form
    387.40/579.90 = 305.80/x
  3. Step 3: Cross multiply
    387.40x = 579.90 × 305.80
  4. Step 4: Simplify right side
    387.40x = 177,333.42
  5. Step 5: Solve for x
    x = 177,333.42/387.40
  6. Step 6: Final answer
    x = 457.75

Related Problems

Find fourth proportional to 193.70, 289.95 and 152.90
Half scale
Find fourth proportional to 774.80, 1,159.80 and 611.60
Double scale
Find fourth proportional to 388.40, 581.40 and 306.80
Similar ratio
Find fourth proportional to 581.10, 869.85 and 458.70
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.