A) The first step needs 100 bricks, the second needs 98, the third needs 96, and so on. Therefore the number of bricks for the nth step is: a_n = a_1 + d(n-1), where a_1 = 100 (the first term), d = -2 (difference).
a_n = 100 - 2(n-1) = 102 - 2n, and for the 30th step, a_30 = 102 - 2*30 = 42. So the top step will need 42 bricks.
b) The total staircase will need: 100 + 98 + 96 + ... +  44 + 42, and there are n = 30 terms. Using the formula for the sum of an arithmetic sequence:
S = (a_1 + a_n)*n/2 = (100 + 42)*30/2 = 2130
Therefore, 2130 bricks are required to build the entire staircase.
        
             
        
        
        
Answer:
D
Step-by-step explanation:
when it's a power of the power we multiply the powers to get a single value for the power.
(6^(1/4))^4=6^(4*(1/4)) (4*(1/4)=1)
=6^1=6
so the answer is D
 
        
             
        
        
        
Most of the information's required for solving the question is already given in the question.
Height of the building that casts a shadow of 20 m = 32 m
Then
Height of the man that casts a shadow of 1.2 m = (32/20) * 1.2 meter
                                                                             = 3.2 * 1.2 meter
                                                                             = 3.84 meter
So the actual height of the person casting a shadow of 1.2 meter is 3.84 meters. I hope that the procedure used for solving the problem is easy enough for you to understand. You can definitely use this method in future for solving problems of similar type without requiring any additional help from outside.
        
             
        
        
        
Not 100% sure this is right but
60cm^2
        
                    
             
        
        
        
1/2 because everything lose half its value points wise.