Sherry Chen's answer to lisaa's Primary 6 Maths Algebra Singapore question.
done
{{ upvoteCount }} Upvotes
clear
{{ downvoteCount * -1 }} Downvotes
Let x be the number of boys at first, which means total savings of boys at first is
(X times $2.80)
After Tom joins with $4.20, the following changes happen:
- the average savings becomes $3
- the number of boys become (x + 1)
- the total savings become [(X x $2.80) + $4.20]
Hence,
[(X x 2.80) + 4.20] = (X + 1) x 3
2.8X + 4.20 = 3X + 3
1.20 = 0.2X
X = 6
So total of boys at the start is 6.
(X times $2.80)
After Tom joins with $4.20, the following changes happen:
- the average savings becomes $3
- the number of boys become (x + 1)
- the total savings become [(X x $2.80) + $4.20]
Hence,
[(X x 2.80) + 4.20] = (X + 1) x 3
2.8X + 4.20 = 3X + 3
1.20 = 0.2X
X = 6
So total of boys at the start is 6.
Date Posted:
4 years ago
360 Tutoring Program