bro the ans is 23
frm 151 to 175 ther r 12 even numbers 152,152..,174
of these
160 has 32(2^5) as factor
152,168 has 8(2^3) as factor
156,164,172 has 4(2^2) as factor
remaining 6 even nos have 2 as a factor
so total number of powers of 2=5+(2*3)+(3*2)+(6*1)=23.
if needed...