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primary 6 | Maths | Algebra
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lisaa
Lisaa

primary 6 chevron_right Maths chevron_right Algebra chevron_right Singapore

please help

Date Posted: 4 years ago
Views: 289
AC Lim
AC Lim
4 years ago
Answer for 1st question = 6
lisaa
Lisaa
4 years ago
thankuu

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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.
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Sherry Chen
Sherry Chen's answer
34 answers (Tutor Details)
1st
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AC Lim
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13108 answers (A Helpful Person)
Hope this helps
For the bottom question, we know each plant’s height in terms of e and they are:

> (2e - 3)
> (4e + 1)
> (e + 2)

So, to find out the total height of all 3, you need to add all of them up:

(2e - 3) + (4e + 1) + (e + 2)
= 2e + 4e + e - 3 + 1 + 2
= 7e

A) total height of plants = 7e

To find out the height of the tallest plant, you’d need to find out what e is.

Since they told you average height of 3 plants is 35cm, so you know the total height of all 3 plants = 35cm x 3 = 105cm.

From part (A),
total height of all plants
= 7 e which is also 105cm.

7e = 105cm
So e = 15cm

So now, you can find out the height of each plant:

> (2e - 3) = 30 - 3 = 27
> (4e + 1) = 60 + 1 = 61
> (e + 2) = 15 + 2 = 17

B) So tallest plant is 61cm.
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Sherry Chen
Sherry Chen's answer
34 answers (Tutor Details)