GCSE Secondary Maths Age 13-17 - Ratio, Proportion & Rates of Change: Direct Proportionality - Explained

The video tutorial addresses a common misconception about proportional relationships. Mary incorrectly claims that doubling N results in D being multiplied by 6. The correct explanation shows that when N is doubled, D should be multiplied by 8, as N is cubed. The video emphasizes the importance of understanding and reasoning in solving such problems, highlighting that the question was straightforward and required only basic reasoning skills.

What did Mary incorrectly claim about the relationship between N and D?

• Doubling N results in D being multiplied by 2.

• Doubling N results in D being multiplied by 4.

• Doubling N results in D being multiplied by 6.

• Doubling N results in D being multiplied by 8.

What is the correct result when N is doubled in the context of D being proportional to N cubed?

• D is multiplied by 4.

• D is multiplied by 6.

• D is multiplied by 8.

• D is multiplied by 2.

What mathematical operation is used to find the new value of D when N is doubled?

• Addition

• Subtraction

• Multiplication

• Division

What was the main reasoning error in Mary's claim?

• She forgot to cube N.

• She added instead of multiplied.

• She used the wrong exponent.

• She calculated 2^3 as 6 instead of 8.

How many marks was the question worth?

• Two marks

• One mark

• Three marks

• Four marks