If `a in N` such that `a N={a x : x in N}` . Describe the set `3Nnn7Ndot`

If a N = { ax : x in N} then the set 4N cap 6N is

If A={x:x=3n,n in N} and B={x:x=4n,n in N} , then find A cap B .

If X={8^n-7n-1 | n in N} and Y={49n-49| n in N} . Then

If X and Y are two sets such that n(X) = 17 , n(Y) = 23 and n (Xuu Y ) = 3 8 , find n(X nnY) .

Observe the following statements : (A) : 10 is the mean of a set of 7 obervations and 5 is the mean of a set of 3 observations. The mean of a combined set is 9. (R ) : If bar(x)_(i)(i = 1,2,…,k) are the means of k - series n_(i)(I = 1,2,3,…,k) respectively, then the combined or composite mean is bar(x) = (n_(1)bar(x)_(1) + n_(2) bar(x)_(2) + ...+ n_(k)bar(x_(k)))/(n_(1)+n_(2)+...+n_(k))

If A = { x : x = 3n-1, n in N and n le 5 } B = { x : x is an odd natural number and x lt 15 } and C = { x : x =4n , n in N and n lt 7 } ,find B cap C

If A = { x : x = 3n-1, n in N and n le 5 } B = { x : x is an odd natural number and x lt 15 } and C = { x : x =4n , n in N and n lt 7 } ,find A cup B

If A = { x : x = 3n-1, n in N and n le 5 } B = { x : x is an odd natural number and x lt 15 } and C = { x : x =4n , n in N and n lt 7 } ,find A cap B

If A = { x : x = 3n-1, n in N and n le 5 } B = { x : x is an odd natural number and x lt 15 } and C = { x : x =4n , n in N and n lt 7 } ,find A cap B

If X and Y are two sets such that n (X)=17, n (Y)= 23 and n (Xuu Y)= 38 find n (X nnY) .