Home / 685.80-1,028.70-253

Finding the Fourth Proportional to 685.80, 1,028.70 and 253

Calculator

Solution

The fourth proportional to 685.80, 1,028.70 and 253 is: 379.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.80 : 1,028.70 = 253 : x
  2. Step 2: Convert to fraction form
    685.80/1,028.70 = 253/x
  3. Step 3: Cross multiply
    685.80x = 1,028.70 × 253
  4. Step 4: Simplify right side
    685.80x = 260,261.10
  5. Step 5: Solve for x
    x = 260,261.10/685.80
  6. Step 6: Final answer
    x = 379.50

Related Problems

Find fourth proportional to 342.90, 514.35 and 126.50
Half scale
Find fourth proportional to 1,371.60, 2,057.40 and 506
Double scale
Find fourth proportional to 686.80, 1,030.20 and 254
Similar ratio
Find fourth proportional to 1,028.70, 1,543.05 and 379.50
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.