Answer:
3times
Step-by-step explanation:
Baking Process: repeatedly rolling out and folding the dough to make layers
Soon Yi starts with a layer of dough = 2millimeters
Each time Soon Yi rolls and folds the dough, the thickness increases by 8 % = 1 + 8 %
When time = 1
Thickness = 2(1 + 8 %) = 2(1+0.08)
= 2(1.08) = 2.16
For time = n
Thickness = 2(1 + 8 %)^n = 2(1.08)^n
When thickness ≥ 2.5mm, n= ?
2.5 = 2(1.08)^n
2.5/2 = (1.08)^n
1.25 = (1.08)^n
Since the numbers are close (1.25 and 1.08), we can compute by multiplying 1.08 by itself till we get 2.5.
1.08 ×1.08× 1.08 = 1.259712
(1.08)³ is a bit above 1.25
2(1.08)³ satisfies the thickness of at least 2.5mm
Let's check our answer using the formula:
When n = 3
2(1.08)³ = 2 × 1.259712 = 2.519424
This satisfies the thickness of at least 2.5mm
Therefore, the smallest number of times Soon Yi will have to roll and fold the dough so that the resulting dough is at least 2.5 mm = 3
