Q&A - PSLE Math

[MathIzzzFun]

mlim321:

Need help on this question:


There were some pens and pencils in a box. When Ali took out 24 pencils, there are 5 times as many pens as pencils left. If he had taken out 60% of the pens from the box instead, he would have twice as many pencils as pens left. How many pens were in the box at first?

TIA!

Hi
after Ali took out 24 pencils,
pens : pencils --> 5u : 1u

at first,
pens : pencils --> 5u : 1u + 24

If 60% of pens is taken out,
pens : pencils --> 2u : 1u + 24 = 1 : 2

cross-multiply/equalize,
4u = 1u + 24
1u --> 8

Number of pens in the box at first --> 5 x 8 = 40

cheers.

[tianzhu]

Essential:

Good nite Tian Zhu , I m back to seek for help. Please help us with this question. A car and a coach travelled from town A and town B. the coach left A at o648 and it took 5 hours to reach town b.the car started 30 mins later than the coach and it took 4 hours to reach town b. at what time did the car catch up with its coach

Hi

Good Morning.

This question has been discussed before.

Hope this helps.

Best wishes

http://farm5.staticflickr.com/4149/4847914819_b35953e42b_z.jpg\">

[Essential]

Good morning , appreciate your detailed Explanation . My DS will understand this better than our own explanation …Thank you and have a great Sunday ahead.

[mlim321]

Thanks MathIzzzFun!


Another question:

Faridah has 190 blue and red beads altogether. 147 of the beads are round in shape, 3/4 of her blue beads and 5/6 of her red beads are round in shape. How many blue beads does she have?

Again thanks!

[tianzhu]

Essential:

Good morning , appreciate your detailed Explanation . My DS will understand this better than our own explanation ...Thank you and have a great Sunday ahead.

Hi

Good Morning

You're welcome.

Have a great weekend too.

Best wishes

[tianzhu]

mlim321:

Faridah has 190 blue and red beads altogether. 147 of the beads are round in shape, 3/4 of her blue beads and 5/6 of her red beads are round in shape. How many blue beads does she have?

Hi

This question touches on simultaneous concept.

You may use MD, Units and Parts or simply represent the variables with letters of the alphabet.

Round ------ 147

Non round ------ 43

BBB + RRRRR ------ 147

B + R ------ 43

BBB + RRR ------ 129

147 -129 ------ 18

This gives RR ------- 18

Hence R ------- 9

B ------ 43 – 9 ------- 34

34*4 ------- 136

Number of blue beads -------136

Best wishes

[match3frog]

Thank you to mathizzzfun and tianzhu for the solutions! Much appreciated

[mlim321]

tianzhu:

BBB + RRR ------ 129

Hi tianzhu,

how do you get \"BBB + RRR = 129\"?

Thanks a lot!

[tianzhu]

mlim321:

Need help on this question:


There were some pens and pencils in a box. When Ali took out 24 pencils, there are 5 times as many pens as pencils left. If he had taken out 60% of the pens from the box instead, he would have twice as many pencils as pens left. How many pens were in the bo at first?

TIA!

Hi

Hope this helps.

Best wishes

http://farm9.staticflickr.com/8002/7477112664_e8392bca38_z.jpg\">

[tianzhu]

mlim321:

tianzhu:

BBB + RRR ------ 129

Hi tianzhu,

how do you get \"BBB + RRR = 129\"?

Thanks a lot!

Hi

B + R ------ 43

(x3)
(3B + 3R ----- 129)

BBB + RRR ------ 129

Best wishes