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Teachers & SchoolsNumber Sense: Drill Set 3, Problem 1. This is a decrease of, approximately, what percent?

Algebra | Percents |

CAHSEE Math | Number Sense |

Language | English Language |

Number Sense | Percentages |

Ratios, Percentages, and Proportions | Percent Change |

This is a decrease of, approximately, what percent?

And here are the potential answers...

Ok, what is this problem testing?

Our ability to recognize that it's a problem involving RATE OF GROWTH ...

or, rate of shrinkage in Tango's case here.

So we'll need the rate of growth formula, which is new minus old over old.

Also note the curveball -- the question is asking for the DECREASE in weight.

Had it asked for the CHANGE in weight, we'd have to think about whether the answer is

a positive or negative number...

...but note in the question set they are all positive, so at least we don't have to worry

about positives and negatives in this problem.

To answer, we just plug in the key terms.

For the NEW weight we look to Tango and his now svelte figure; he weighs in at 155 pounds.

A big improvement from his former, hefty weight of 180 pounds.

So new minus old over old gets us 155 minus 180 over 180...

...which boils down to 25 over 180, which reduces further to 5 over 36.

Now just some careful long division to calculate the percentage and we're there.

36 goes into 5... to get us roughly 14%.

As in all of these types of questions, this is the BEST answer, not the PERFECT answer.

Which is just fine... as Daisy isn't really looking for perfect.