If the cost of a cell phone has decrease 400% during the past 10 years, does that correspond to a cost decrease of 4 times

If the cost of something decreases by 100% the resulting cost is zero.

It can not decrease by more than 100%

No, a decrease of 400% does not correspond to a cost decrease of 4 times. In fact, a decrease of 400% means that the cost has reduced by four times its original value.

To understand this, we can use a simple formula:

Cost decrease percentage = ((Initial Cost - Final Cost) / Initial Cost) * 100%

In this case, let's assume the initial cost of the cell phone was $100.

400% decrease = ((100 - Final Cost) / 100) * 100%

Simplifying the equation:

4 = (100 - Final Cost) / 100

Now, cross-multiply:

4 * 100 = 100 - Final Cost

400 = 100 - Final Cost

Rearrange the equation to find the Final Cost:

Final Cost = 100 - 400

Final Cost = -300

As you can see, the result is negative, indicating that the cost decrease of 400% is in relation to the original cost. So, the final cost would be -$300, which does not make sense in practical terms. Therefore, this implies an error in the given information or calculation.

To summarize, a decrease of 400% means the cost has reduced by four times its original value, resulting in a negative final cost.