Question 113(iii)

Sunscreens block harmful ultraviolet (UV) rays produced by the sun. Each sunscreen has a Sun Protection Factor (SPF) that tells you how many minutes you can stay in the sun before you receive one minute of burning UV rays. e.g. If you apply sunscreen with SPF 15, you get one minute of UV rays for every 15 minutes you stay in the sun. A label on a sunscreen with SPF 30 claims that the sunscreen blocks about 97% of harmful. UV rays. Assuming the SPF factor is accurate, is this claim true. Explain.

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Solution

False,
According to the claim, for $\frac{3}{100}$ affect of UV rays.
1 minute = $33 \frac{1}{3}$ SPF
Affect $\neq 30$ SPF claim

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Question 113(iii)

Sunscreens block harmful ultraviolet (UV) rays produced by the sun. Each sunscreen has a Sun Protection Factor (SPF) that tells you how many minutes you can stay in the sun before you receive one minute of burning UV rays. e.g. If you apply sunscreen with SPF 15, you get one minute of UV rays for every 15 minutes you stay in the sun. A label on a sunscreen with SPF 30 claims that the sunscreen blocks about 97% of harmful. UV rays. Assuming the SPF factor is accurate, is this claim true. Explain.

Question 113(ii)

Sunscreens block harmful ultraviolet (UV) rays produced by the sun. Each sunscreen has a Sun Protection Factor (SPF) that tells you how many minutes you can stay in the sun before you receive one minute of burning UV rays. e.g. If you apply sunscreen with SPF 15, you get one minute of UV rays for every 15 minutes you stay in the sun.
- Suppose, a sunscreen allows 25% of the sun's UV rays.
(a) What fraction of UV rays does this sunscreen block? Give your answer in lowest terms.
(b) Use your answer from part (a) calculate this sunscreen's SPF. Explain how you found your answer?

Q. _____ is the allotropic form of element ____ protects us from the harmful ultraviolet rays (UV rays) from the sun.

Q. _______ protects us from the harmful UV rays of the sun.

___ is the allotropic form of Oxygen $(O_{2})$ that protects us from the harmful ultraviolet rays(UV rays) from the Sun.

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False, According to the claim, for 3100 affect of UV rays. 1 minute = 3313 SPF Affect ≠30 SPF claim

False,
According to the claim, for $\frac{3}{100}$ affect of UV rays.
1 minute = $33 \frac{1}{3}$ SPF
Affect $\neq 30$ SPF claim