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primary 6 | Maths
| Ratio
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Date Posted: 3 years ago
Views: 205
a) 8
b) boy = 26.
Girl = 14
b) boy = 26.
Girl = 14
Ok. I am thinking of average should use 73.2 or 73.4 ... cause if average use 73.2 for b). Boy = 28, girl = 12
Sometimes I find primary school questions more challenging than A Maths questions...
Let me have a look.
Let me have a look.
The question seems to be really ambiguous, because they wrote that the average score was calculated as 73.2. They did not state that it had to be the OVERALL average score of the GROUP.
Weird.
Having said that, I will assume that the average score of the boys is correctly calculated at 72 and the average score of the girls is correctly calculated at 76 (if I do not make this assumption, the "erroneous score" will also affect either the 72 or the 76 average).
Weird.
Having said that, I will assume that the average score of the boys is correctly calculated at 72 and the average score of the girls is correctly calculated at 76 (if I do not make this assumption, the "erroneous score" will also affect either the 72 or the 76 average).
Actual correct score
= 40 x 73.4
= 2936
"Miscalculated" score
= 40 x 73.2
= 2928
Error in counting
= 2936 - 2928
= 8 marks (lower than it should have been)
= 40 x 73.4
= 2936
"Miscalculated" score
= 40 x 73.2
= 2928
Error in counting
= 2936 - 2928
= 8 marks (lower than it should have been)
Precisely i had a hard time explain to my daughter to get her understanding of the concept.
Anyway thank you so much guys attempt to the qns. Appreciate it
We will proceed to do guess and check here (assumption approach by AC Lim works perfectly well too!).
Since the total number of marks of the 40 students is 2936, we need to find two numbers A and B (which add up to 40) so that
Total score of boys + Total score of girls = 2936
A x 72 + B x 76 = 2936.
A is for the boys, B is for the girls.
Let's try A = 20, B = 20. The overall result is 2960, which is higher than 2936. We must reduce the number of girls and increase the number of boys to bring down the 2960 to 2936.
Working out (after a few tries), A = 26, so there are 26 boys.
Since the total number of marks of the 40 students is 2936, we need to find two numbers A and B (which add up to 40) so that
Total score of boys + Total score of girls = 2936
A x 72 + B x 76 = 2936.
A is for the boys, B is for the girls.
Let's try A = 20, B = 20. The overall result is 2960, which is higher than 2936. We must reduce the number of girls and increase the number of boys to bring down the 2960 to 2936.
Working out (after a few tries), A = 26, so there are 26 boys.
It is also noteworthy to know that we cannot take the average of two averages to obtain an overall average.
By this, we cannot say that...
...just because the average score of the boys is 72 and the average score of the girls is 76, then the overall average score is 74..."
as evidenced in this question.
We have no choice but to compute the total scores across everyone being considered.
By this, we cannot say that...
...just because the average score of the boys is 72 and the average score of the girls is 76, then the overall average score is 74..."
as evidenced in this question.
We have no choice but to compute the total scores across everyone being considered.
Look like question is not clear. Any answer from answer sheet?
The teacher says will explain it after the sch reopens..
Will share with you guys once i have it
Thanks once again
Will share with you guys once i have it
Thanks once again
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Hope this is correct for b). Hope J or Eric or snell can give comments. Hope this helps.
Date Posted:
3 years ago
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