0
$\begingroup$

In one of our questions in school, we are asked,

For a given index finger length which of the following groups has the longest ring finger if the $2$D:$4$D ratio is:

Group A $0.96$,

Group B $0.98 $

Group C $0.99$ and

Group D $1.01$.

[Definition: $2$D:$4$D ratio means the ratio of the length of the index finger(2D) to ring finger (4D)]

The answer is Group A but I'm finding it very difficult to understand this especially with zeros involved in the ratios. I would be very grateful if someone could explain where the answer came from and how you got it. Thank you.

$\endgroup$
  • $\begingroup$ Maybe it is easier for you if you consider the 4D:2D ratio, which is always the reciprocal of the 2D:4D, for example for group A it is $\frac1{0.96}\approx 1.04$ and so no longer has that pesky zero $\endgroup$ – Hagen von Eitzen Feb 17 at 12:28
0
$\begingroup$

The $2D:4D$ ratio essentially represents $\frac{2D}{4D}$ , where $2D$ is the length of the index finger , and $4D$ is the length of the ring finger .

We are given that $2D$ is constant . Therefore , we have :-

For group A:- $\frac{2D}{4D} =0.96 \implies 4D = \frac{2D}{0.96}$

For group B:- $4D=\frac{2D}{0.98}$

For group C:- $4D=\frac{2D}{0.99}$

For group D:- $4D=\frac{2D}{1.01}$

Now recall that for a fraction $\frac{a}{b}$ , the greater the denominator $b$ , the smaller the fraction . The denominator is least in case of group A , and hence $4D$ is greatest , for group A.

$\endgroup$
  • $\begingroup$ Thank you! This helps a lot $\endgroup$ – Michelle Feb 17 at 14:22

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.