A. CHild jumping rope can jump at a speed of 280 revolutions every two minutes what is the number of revolutions the child can jump in 3.5 minutes

the number of revolutions the child can jump in 3.5 minutes is 490 .

Step-by-step explanation:

Here we have , A child jumping rope can jump at a speed of 280 revolutions every two minutes . We need to find what is the number of revolutions the child can jump in 3.5 minutes . Let's find out:

According to question , A child jumping rope can jump at a speed of 280 revolutions every two minutes  , So in one minute Number of revolutions is :

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Now , the number of revolutions the child can jump in 3.5 minutes :

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Therefore , the number of revolutions the child can jump in 3.5 minutes is 490 .

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.

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