Answer: The sets are:
b and d.
Step-by-step explanation:
A set is a collection of distinct objects, a set must be well defined, and it can contain numbers, people, objects, etc. (sets can contain infinite elements, for example, the set of the real numbers has infinite elements)
A) The current U.S senators from Texas.
Ok, the "current U.S senators from Texas" depend on when this is read. For example, the senators of today will not be the same as the senators in 10 years from now.
So the elements of this set today are not the same as the ones in 10 years, then this is not a well defined set.
A weel defined set in this case, would be:
"The U.S senators from Texas for the year 2020"
So this is a set of numbers, we know that 1987 is a prime number, so the only prime number that divides 1987 is 1987.
Then this set is {1987}
is well defined.
c) All the people in Mexico.
A person is well defined.
So when i say "all the people in Mexico has for now" we can find all those "elements" and make a set with them.
But the people in Mexico change, so the elements of this set actually depend on when this is read, so this is not well defined.
D) Al the prime numbers between 8 and 10.
Well, we do not have any prime number between 8 and 10, so this is an empty set:
{∅}
