Home / 687.80-1,031.70-255

Finding the Fourth Proportional to 687.80, 1,031.70 and 255

Calculator

Solution

The fourth proportional to 687.80, 1,031.70 and 255 is: 382.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.80 : 1,031.70 = 255 : x
  2. Step 2: Convert to fraction form
    687.80/1,031.70 = 255/x
  3. Step 3: Cross multiply
    687.80x = 1,031.70 × 255
  4. Step 4: Simplify right side
    687.80x = 263,083.50
  5. Step 5: Solve for x
    x = 263,083.50/687.80
  6. Step 6: Final answer
    x = 382.50

Related Problems

Find fourth proportional to 343.90, 515.85 and 127.50
Half scale
Find fourth proportional to 1,375.60, 2,063.40 and 510
Double scale
Find fourth proportional to 688.80, 1,033.20 and 256
Similar ratio
Find fourth proportional to 1,031.70, 1,547.55 and 382.50
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.