The answer is D. <span>No, it is not a valid inference because his classmates do not make up a random sample of the students in the school.</span>
To empty the pool, you need to lower the water level by 150cm. since you can only lower it by 30cm every 2 hours (also same as 15 cm per hour), that means it will take you 10 hours.
150cm*(2 hours)/(30cm) = 150*(1/15) = 150/15 = 10.
6 a.m. + 10 hours = 4 p.m.
So the answer is C.) 4 p.m.
<span>0.8, 7/8 = .875 , 81% = .81, 19/25 = .76
</span>from least to greatest: 19/25, 0.8, 81%, 7/8
perimeter = 2 l + 2w
here l = 15 and w = 4
perimeter = ( 2 × 15 ) + ( 2 × 4 ) = 30 + 8 = 38cm
