Find the percent of change in altitude if a weather balloon moves from 50 ft to 190 ft. Describe the percent of change as an increase or decrease. Round to the nearest tenth if necessary. a. 238%; increase
b. 280%, increase
c. 86.9%; decrease
d. 280%; decrease

Of course the percentage is an increase. If it moves from 50ft to 190 ft its an increase. So you can automatically cross out “c” and “d”.

Now just think about it logically. This can save you from a lot of work.

So you have it from 50ft to 190 ft.

Use 100% place holders.

50ft*100 percent is 50

50ft*200 percent is 150

Now your somewhere close near the 190 ft range.

THink about the last two options, you can ignore the 200 percent since thats what we used as the closest possible place holder.

Now use 50% place holders.

50% of 50 is 25.

so 175 is the closest we can get with 250%

Now we still have about a 15 ft space.

250% is obviously greater then 238% so we can elimate that option.

The final answer is (B)

Step-by-step explanation:

If wanted proof

So we discussed this logically but if you want it mathematically below is the explanation:

50ft to 190 ft.

To calculate percentage of change you want to first find the distance.

190-50=140

Theres a 140 ft change.

Now you can use proportions

50/1 = 140/x

The 50/1 represents 50 feet for 100 percent or 1

The 140 represents 140 feet for (x) feet since its unknown

now cross multiply

50*x

140*1

50x=140

Now solve

140/50=2.8

2.8 is the deciaml If you convert it to a percentage you just multiply it by a hundred since percent means out of a hundred.

2.8 out of a hundred it 280%

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