Aman who is 2 meters tall is facing a tower that is 13 meters away. he can see the reflection of the top of the tower in a puddle that is 0.5 meter in front of him. what is the approximate height of the tower in meters?

The concept that can be used in order to answer this item is that of ratio and proportion. The ratio of the man's height and the length of his shadow should be proportional or equal to the ratio of the tower height and length of its shadow. If we let x be the height of the tower, the equation that would help us solve this item is,
             
                        2 / x = 0.5 / 13.5
The value of x is equal to 54. Thus, the tower's height is approximately 54 meters. 

1. 0.3 •4 is the same as 4 groups of 0.32. 7•0.8 is the same as 7 groups of 0.83. it increases by 0.5 every time, so 0.5x4 it increases by 0.9 every time, so 0.9x5. 0.9•12=10.86. 0.47•5=2.35i can finish the next ones in a separate post