Q&A - P5 Math

[tianzhu]

yamhh:

Need help for the below question:-

The average height of a group of children was 139.4cm. When Mr Tan measured and recorded the height of these children, he wrongly recorded one child's height as 192cm when it should have been 129cm. As a result, Mr Tan calculated the average height as 142.4cm. How many children were there in the group?

Many thanks in advance...

Yam

Hi

Good Morning.

192 – 129 ----- 63

142.4 – 139.4 ----- 3

Number of children ------ 63/3 ------ 21

Best wishes

[yamhh]

Many thanks who replied my question.

[yamhh]

Many thanks for help.

[happyheart]

I need help with this question please.


Q) A bus left the interchange with some passengers on board. At bus stop A, 10 passengers boarded the bus. When it reached bus stop B, 3/4 of the passengers alighted. The bus continued its journey and at bus stop C, 2/3 of the passengers alighted while 3 passengers boarded the bus. There were 18 passengers on the bus when it left bus stop C. How many passengers were on the bus when it left the interchange?

[tianzhu]

happyheart:

I need help with this question please.


Q) A bus left the interchange with some passengers on board. At bus stop A, 10 passengers boarded the bus. When it reached bus stop B, 3/4 of the passengers alighted. The bus continued its journey and at bus stop C, 2/3 of the passengers alighted while 3 passengers boarded the bus. There were 18 passengers on the bus when it left bus stop C. How many passengers were on the bus when it left the interchange?

Hi

You may use a strategy called “Working backwards”.

A neat way is to break up the question into parts. You may use MD or units.

18 – 3 ------ 15

1 unit ------ 15

2 units ------ 30

45 passengers moved from B to C.

1 part ------ 45

3 parts ------ 135

Number of passengers moving from A to B -------- 45 + 135 ------- 180

At A, 10 passengers boarded.

Hence, number of passengers when leaving interchange ------- 180 – 10 ------ 170

Hope this helps.

Best wishes

[YumYum]

Hi, can anyone pls help with this Qn?


Is there a way to solve this qn other than guess n check:

A group of adults and children paid o total of $586.60 for admission fees to the Jurong Bird Park. Each adult had to pay $25.50 while each child paid $15.70
a.) How many adults were there?
b.) How many children were there?

[tianzhu]

YumYum:

Hi, can anyone pls help with this Qn?


Is there a way to solve this qn other than guess n check:

A group of adults and children paid o total of $586.60 for admission fees to the Jurong Bird Park. Each adult had to pay $25.50 while each child paid $15.70
a.) How many adults were there?
b.) How many children were there?

Hi

Just curious, where is this question from? I’ve have not seen such questions before.

With some logical reasoning, one should be able to get 15 adults and 13 children

To check

(15*25.5) + (13*15.7) ------ 382.5 + 204.1 ------- 586.6

Best wishes

[YumYum]

Thanks, Tianzhu.


It’s from my dd’s school paper.

[happyheart]

tianzhu:

happyheart:

I need help with this question please.


Q) A bus left the interchange with some passengers on board. At bus stop A, 10 passengers boarded the bus. When it reached bus stop B, 3/4 of the passengers alighted. The bus continued its journey and at bus stop C, 2/3 of the passengers alighted while 3 passengers boarded the bus. There were 18 passengers on the bus when it left bus stop C. How many passengers were on the bus when it left the interchange?

Hi

You may use a strategy called “Working backwards”.

A neat way is to break up the question into parts. You may use MD or units.

18 – 3 ------ 15

1 unit ------ 15

2 units ------ 30

45 passengers moved from B to C.

1 part ------ 45

3 parts ------ 135

Number of passengers moving from A to B -------- 45 + 135 ------- 180

At A, 10 passengers boarded.

Hence, number of passengers when leaving interchange ------- 180 – 10 ------ 170

Hope this helps.

Best wishes

Thank you, Tianzhu. My DS used branching method and he can derive the same answer for this question. Is there a risk in using branching for this type of Qns?

[tianzhu]

happyheart:

Thank you, Tianzhu. My DS used branching method and he can derive the same answer for this question. Is there a risk in using branching for this type of Qns?

Hi

You're welcome.

Whether MD, UM or BM, one should arrive at the same answer. Use the method the child is comfortable with.

Best wishes