On a sunny day mark can stay in the sun for 20 minutes before he gets sunburnt. he wants to sunbathe for 3 hours. what is the lowest level of sun protection that he should use : 5, 15, 20, 30, 50
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the "power" of a lens is its resolution power, or its ability to distinguish between to closely located points. with the low power lens, it is likely you will see the rough form of the hay and maybe some movement of dots around the hay. however, when observed with the high power lens, the detailed features of the hay become visible and the microbes being grown are more clearly visible.

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