Is 1u represent the no of rows?

Yes, you're right...

To find the number of dots on each figure: Fig 2 -- 1 + 2 = = 3 (Short cut: 2x3÷2=3) Fig 3 -- 1 + 2 + 3 = 6 (Short cut: 3x4÷2=6) Fig 4 -- 1 + 2 + 3 + 4 = 10 (Short cut: 4x5÷2=10) So for Fig 15 -- 1+2+3+...........+15 = Ans (Short cut: ___x___÷2) :)

Thanks

1 and 14 is 15.. 2 and 13 is 15 Repeat until 7 and 8 is 15 Then just add last 15.. Basically 15 ×7 + 15 Or 15 ×8= ans

(15 + 1) x (15/2) = 120

Siti NurBatrisya

Mike, from your solution, is this the formula?

for this type of pattern, it can be observed that Tn ＝n × (n+1) ÷2 where Tn is the number of dots in the nth pattern.

Why divide by 2?

if u were to shift all the dots of any pattern number to aligned to the left to form a right triangle, u realise the triangle has height "n"and breadth "n+1". it has HALF the number of dots as a RECTANGLE with dimensions n by (n+1.)

Thank you Mr yeo

Mai keh ki.

Mr yeo, how do you know that 3u is 25%?

R sold 25% lesser than S. Therefore the ratio of sales of S:R is 4:3.

So 1u=25%?

Yes

Yeo See Yeong sir. . Dint understand the final part at all...can explain more pl.

R sold 3u. So he us left with 162 - 3u . Since S is left with twice the amount to R, so S will have to sets of (162 - 3u).

Also, we know that S sold 4u. He had 162 +74 originally. Hence, he will have 162 + 74 - 4u eventually.

The ans given is 100Y +5/2

I am not sure if the given answer is correct. Looks like it uses cm instead of m. Even if it uses cm, answer shd be 50Y + 5/2, I think.

Shu Hao can u help