51
There are 12 points in a plane of which 5 points are collinear, then the number of lines obtained by joining these points in pairs is ${ }^{12} C_2-{ }^5 C_2$.
A
TRUE
B
FALSE
52
Three letters can be posted in five letter boxes in $3^5$ ways.
A
TRUE
B
FALSE
53
In the permutations of $n$ things $r$, taken together, the number of permutations in which $m$ particular things occur together is ${ }^{n-m} P_{r-m} \times{ }^r P_m$.
A
TRUE
B
FALSE
54
In a steamer there are stalls for 12 animals and there are horses, cows and calves (not less than 12 each) ready to be shipped. They can be loaded in $3^{12}$ ways.
A
TRUE
B
FALSE
55
If some or all of $n$ objects are taken at a time, then the number of combinations is $2^n-1$.
A
TRUE
B
FALSE