Question

The weight of a bar of soap decreases by 2.5% each time it is used. If the bar weighs 95 grams when it is

new, what is its weight to the nearest gram after 15 uses?
what formula do I use ​

Answer 1

To find the weight of the soap after 15 uses, calculate the new weight after each use by subtracting 2.5% of the old weight. Repeat this calculation 15 times to find the weight after 15 uses, which is approximately 77 grams.

Step-by-step explanation:

To find the weight of the soap after 15 uses, we need to calculate the new weight after each use. The weight of the soap decreases by 2.5% each time it is used. We can use the formula:

New weight = Old weight - (2.5% of Old weight)

Now let's calculate the weight after 15 uses:

1. Old weight = 95 grams
2. Calculate the decrease in weight after each use: 2.5% of 95 grams = 2.375 grams
3. Calculate the new weight after each use: 95 grams - 2.375 grams = 92.625 grams
4. Repeat this process 15 times: 92.625 grams - 2.375 grams = 90.25 grams (after 1 use)
5. Continue the calculations: 90.25 grams - 2.375 grams = 87.875 grams (after 2 uses)
6. Keep repeating until we reach 15 uses: 84.5 grams, 81.125 grams, 77.75 grams, etc.

After 15 uses, the weight of the soap is approximately 77 grams.

Answer 2

9514 1404 393

Answer:

65 grams

Step-by-step explanation:

The formula for an exponential sequence is ...

w(n) = (initial weight) × (1 - (decrease per use))^n . . . . for n uses

w(n) = 95·0.975^n . . . . . filling in the given numbers

Then for 15 uses, the weight is ...

w(15) = 95·0.975^15 ≈ 64.98 ≈ 65

The weight after 15 uses is about 65 grams.