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Adrian Ng

Asked 9 years ago

SG Primary 5 Statistics

Making it visual...

Replies 1

Dorothy Tan

Thanks. Much appreciated 👍👏😊

6 years ago

Ellen Cheong

Asked 9 years ago

SG Primary 4 Number and Algebra

Please help. Thanks in advance.

Replies 7

Maggie Lukes

Try using guess and check. .40(#apples) + .60(#starfruits) = 15.20. Start with 15 of each and keep trying until you find the right combination.

6 years ago

Desmond Tan

Assuming all 30 are apples, the cost will be 0.40x30=$12 So there is an extra of $15.20-$12=$3.20. This must be due to the extra cost incurred from buying star fruits instead of apples. (Extra cost of buying 1 starfruit instead of 1 Apple is 60-40=20 cents) $3.20/$0.20=16. So 16 are starfruits while 14 are apples. Hence 16-14=2 more starfruits than apples.

6 years ago

Ellen Cheong

Thanks both!

6 years ago

Xavier Sng

One of my students suggested the following: If one notices the total cost of an Apple and a starfruit is $1, and that 15 of each fruit cost a total of $15, which is $0.20 less than the actual amount of $15.20 spent. One also knows that a starfruit costs 20 cents more than an Apple. Hence if one of the 15 apples is converted into a starfruit, there will be 2 more starfruits than Apples.

6 years ago

Xavier Sng

The above is a "non-standard" solution, but an observant and sharp student can easily arrive at the answer mentally and later present the solution using a "standard" method. This gives the student an extreme advantage, but do take note that not every question provides numbers for this kind of exploitation.

6 years ago

Ellen Cheong

Thanks, Xavier Sng!

6 years ago

Xavier Sng

The pleasure is mine. Regards

6 years ago

Sunil Rawal

Asked 9 years ago

SG Primary 5 Number and Algebra

Please help me with this question from primary 5

Replies 1

Desmond Tan

Work backwards 163-18=145 (which is 5 parts out of 9) 145/5 x 9=261 (number of pens before Xavier took out) 261+19=280 (which is 5 parts out of 7) 280/5 x 7= 406 (number of pens before Yogi took out) 406-6=400 (number of pens before Zed put back 6 pens, this is also 40%) 400/40 x 100=1000 (number of pens in the box at first)

6 years ago