D1,..,d9 = 0,0,2,2,2,3,4,6,8 //there are 9 values, in ascending order Q2 (median) = d5 = 2 //value in the middle Q1 = (d2+d3) / 2 = (0+2)/2 = 1 (Q1 is middle value of d1,d2,d3,d4, but there is no middle element among four elements, that is why arithmetic mean is taken) Q3 = (d7+d8) / 2 = (4+6)/2 = 5 interquantlie range = IQR = Q3 - Q1 = 5 -1 = 4 answer: 4
Suppose that a and b are any n-vectors. Show that we can always find a scalar γ so that (a − γb) ⊥ b, and that γ is unique if . Recall that given two vectors a,b a⊥ b if and only if where is the dot product defined in . Suposse that . We want to find γ such that . Given that the dot product can be distributed and that it is linear, the following equation is obtained
Recall that are both real numbers, so by solving the value of γ, we get that
By construction, this γ is unique if , since if there was a such that , then