If the cost of a cell phone has decreased 400% during the past 10 years, does that correspond to a cost decrease of four times?
It makes no sense to me. It says the price went from +x to -3x, so they are paying you three times the original price just to give them away.
Since the cell carriers make their big money on the service charges, sometimes such giveaways make sense.
I suspect whoever wrote that question does not know what a 400% decrease means.
Thanks for the input.
Actually is does make sense. drwls misinterpreted the question. It's asking for a decrease of 400% over 10 year and NOT a percent decrease. This means, that for year 1, the cost of a cell phone drop by 40%. At year 2 it dropped by another 40%, and on and on until year 10. So 40%+40%+40%+40%+40%+40%+40%+40%+40%+40% = 400%.
So assume at year 1 the cost of a phone is $100. Then at year 2 it will be $60 since (1-0.4)*100=60. Using the same process, at year 3 it will be $36....Finally, at year 10, it's $1.00.
This is not the same as claim the prince dropped by 4 time over 10 years.
No, a decrease of 400% does not correspond to a cost decrease of four times. In fact, a decrease of 400% indicates a much larger decrease than four times.
To understand why, it's important to know what a change of 400% means. A decrease of 400% means that the new value is 400% less than the original value (which is equivalent to 4 times the original value). Mathematically, this can be expressed as:
New Value = Original Value - (400% of Original Value)
To calculate the decrease in value, we need to find out what 400% of the original value is. To do this, we can multiply the original value by 400% (which is equivalent to multiplying by 4 since 100% = 1):
400% of Original Value = 4 * Original Value
So, the decrease in value is equal to 4 times the original value. This means that the cost has decreased by four times.
However, keep in mind that when we say the cost has decreased 400%, it means the new value is 400% less than the original value. In other words, the new cost is 100% - 400% = -300% of the original cost. Negative values do not make sense in this context, so we can interpret a 400% decrease as a cost decrease of 4 times the original value (not four times less).