# Janitor a can clean all the classrooms at strawberry school in 8 hours. janitor b can clean the same classrooms in 10 hours.

###### Question:

working together, to clean all the classrooms?

## Answers

9 hours

Step-by-step explanation:

together, 1/of 8 is 4 and 1/2 of 10 is 5 4+5=9

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step-by-step explanation:

[tex]7.00 \cdot 10^{-7} m - 1\cdot 10^{-3} m[/tex]

explanation:

infrared radiation has wavelength in the range between 700 nm and 1 mm. lets' convert these values into scientific notation, keeping in mind that:

[tex]1 nm = 10^{-9} m\\1 mm = 10^{-3} m[/tex]

let's start from the lower value, we have:

[tex]700 nm = 700 \cdot 10^{-9} m = 7.00 \cdot 10^{-7} m[/tex] (we moved the dot two places to the left, so we increased the exponent by 2 units, from -9 to -7)

the higher value is:

[tex]1 mm = 1 \cdot 10^{-3} m[/tex]

so, the range of wavelength of infrared radiation is:

[tex]7.00 \cdot 10^{-7} m - 1\cdot 10^{-3} m[/tex]