Answer:
A control should have been included in the investigation
Explanation:
It is impossible for the student to interpret a correct conclusion about his experiment, without adding a control treatment where he can really compare the differences between the variables.
Control treatment is an element of research that receives all factors, except the variable being tested. The control serves to make comparisons with the other treatments, allowing to observe the exact difference between a system where the variable was tested and the system where it was not.
In the case of the question above, it would have been necessary for the student to have placed a cart on a ramp of normal height and without sandpaper. That way he could compare the speed between this cart and the carts on the other ramps, thus having a correct result.
<em>The Constitutional Convention</em> was also called "<em>The Federal Convention</em>" and "<em>The Philadelphia Convention</em>", came about between May and September of 1787 in order to tackle issues and weak spots left by the <em>Articles of Confederation</em> in the central government.
<em>"At the constitutional convention, the delegates agreed that slaves would be counted as </em><em>three-fifths</em><em> of a person</em>..."
The Cello<span> is much larger and lower than the viola, and must be played while sitting with the instrument between the knees. Fortunately, cellos are made for students of all sizes.
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The Violin<span> is the smallest, and is therefore the highest in pitch. It is also the most popular. It is played with the instrument under the chin while sitting or standing, and its small size makes it easily transporable.
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From the information I know at this time i believe it is C.
hope this helps
