Ask Singapore Homework?

Upload a photo of a Singapore homework and someone will email you the solution for free.



Question

primary 5 | Maths | Percentage
2 Answers Below

Anyone can contribute an answer, even non-tutors.

Answer This Question
Blink_reveluv
Blink_reveluv

primary 5 chevron_right Maths chevron_right Percentage chevron_right Singapore

Help

Date Posted: 3 weeks ago
Views: 17
Eric Nicholas K
Eric Nicholas K
3 weeks ago
You will need to do grouping for this question and consider the notes as “unit-notes”.

20% of the notes are $10 notes.
40% of the remainder are $5 notes. Be careful because the word remainder is used here.
The rest are $2 notes.
The total value of the notes is $1026.

Let there be 100 units of notes (because I see a percent, I use 100 units).

20 units are $10 notes, since 20% of 100 units is equal to 20 units (which is why I used 100 units)

There are 80 units left at this point. 40% of these 80 units are $5 notes.

So 32 units are $5 notes and 48 units are $2 notes.

20 units are $10 notes.
32 units are $5 notes.
48 units are $2 notes.

I will label the total value of the notes as unit-notes.

The total value of the $10 notes is 20 x 10 = 200 unit-notes.

The total value of the $5 notes is 32 x 5 = 160 unit-notes.

The total value of the $2 notes is 48 x 2 = 96 unit-notes.

These add up to 456 unit-notes, which is numerically $1026 in value.

456 unit-notes = $1026
1 unit-note = 1026/456 = $2.25

Now we can work out the rest.

200 unit-notes = 200 x 2.25 = $450
160 unit-notes = 160 x 2.25 = $360
96 unit-notes = 96 x 2.25 = $216

Total value of $10 notes is $450.
Total value of $5 notes is $360.
Total value of $2 notes is $216.

Number of $10 notes = 450/10 = 45
Number of $5 notes = 360/5 = 72
Number of $2 notes = 216/2 = 108

Total number of notes
= 45 + 72 + 108
= 225
J
J
3 weeks ago
Or since one unit is found,

Total units = 100 x 2.25 = 225

I was going on the 2.25 route initially but decided to simplify the ratio since some students dislike decimals and will attempt to round down without realising the number of notes will end up being a whole number

See 2 Answers

$10 notes are 20% of total
Remainder : 100% - 20% = 80% of total
5 dollar notes are 40% of remainder.
40% is 40/100 and 40/100 = 2/5
So $5 notes are 2/5 of remainder.
2/5 of remainder = 2/5 x 80% of total = 32% of total
$2 notes = 100% - 32% - 20% = 48% of total
Ratio of $10 notes : $5 notes : $2 notes = 20 : 32 : 48
= 5 : 8 : 12

Based on the info above, we can group 12 $2 notes, 5 $10 notes and 8 $5 notes into 1 set. 5 + 8 + 12 = 25, so there are 25 notes in a set.

Value of notes in 1 set
= $2 x 12 + $10 x 5 + $5 x 8
= $24 + $50 + $40
= $114

Since there's a total of $1026, number of sets = $1026 ÷ $114 = 9
Total number of notes = 9 sets x 25 per set = 225
done {{ upvoteCount }} Upvotes
clear {{ downvoteCount * -1 }} Downvotes
J
J's answer
191 answers (A Helpful Person)
1st
J
J
3 weeks ago
Is there an issue with the answer?
Eric Nicholas K
Eric Nicholas K
3 weeks ago
There is nothing wrong with the answer and in fact it is a clear valid approach.

J is an experienced tutor in this field.
done {{ upvoteCount }} Upvotes
clear {{ downvoteCount * -1 }} Downvotes
AC Lim
Ac Lim's answer
2682 answers (A Helpful Person)
The other tutors answer were correct. Hope the model help for better visualize in explanation. Hope this helps