We can help you most effectively if you write to us directly via Ask a Question, showing a specific example you are having trouble with, and what you have tried. Then we can discuss your difficulties in detail there.

]]>Clearly you did not follow the formula discussed in this post, as the numerator is supposed to be N/2 – F = 50/2 – 23 = 2, not 2.5.

Why do you think you should use (N+1)/2 instead of N/2? Were you taught it, or were you thinking as Pramod did in this post, and doing what felt right to you? I demonstrated that his formula was wrong, *under my assumptions*; but I understand why one might *think* it was right.

Of course, the formula is not exact, providing only a reasonable guess as to the actual median of data that are not available to us; so we can’t really talk about it being “correct” in the first place. But I showed the conditions under which it would be “exact” — though at the end I pointed out that those conditions do not really hold for a discrete distribution, which is what yours is, in contrast to Pramod’s.

]]>This is the response I have worked when asked to obtain median for the data given.Is there any mistake when I consider the median as being in the 25.5th position rather than 25th position as I have done??

Ht (cm). Freq

140-144. 8

145-149. 15

150-154. 14

155-159. 11

160-164. 2 ]]>

I think you, like others, will benefit from reading the follow-up post, Long Division with Zero, Revisited, which starts with an example very similar to yours.

Another approach to showing that 5.2 is wrong is just to **do the multiplication that corresponds to the division**. If you say that 653 / 13 = 5.2, then you are saying that 653 = 13 * 5.2. But 13 * 5.2 = 67.6, not 653. This is how we **check** divisions; and teaching your son to do that regularly can help him catch this sort of mistake, as well as better understand what division is.

Of course, since your answer is rounded, not exact, if you check 653 / 13 = 50.2, you find that 13 * 50.2 = 652.6, not exactly 653; but clearly it’s close.

It would also be good to teach him how to **check by estimation**. 653 / 13 should be close to, say, 600/10 = 60, and 5.2 is very far from that.

But ultimately, the explanation for why his **work** is wrong is, as I say in the newer post, “Never ignore a quotient.” You’ll see what I mean when you read it.

It is actually taught that way worldwide. Only north American teachers differ but everybody do traditional algebra the same way even the North Americans. That should be proof enough. It only became a problem after computers or calculators couldn’t comprehend this. U don’t change centuries of algebra because a machine can not comprehend it, u improve the machine. Now there are calculators that do understand this.

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