When I was 4 years old my sister was half my age, now am 100 how old is my sister? 

Expert Answers
rogal eNotes educator| Certified Educator

You can make use of equations.

For instance, let the number of years you need to grow to become 100 years old be x. Then

4 + x = 100

x = 100 - 4 = 96

When you are 4 years old, your sister is half your age, that is, 0.5 x 4 = 2 years old.

Your sister grows for 96 years to become 2 + 96 = 98 years, when you are 100 years old.

justaguide eNotes educator| Certified Educator

When you were 4 years old, your sister was half your age. Half of 4 is 2, your sister was 2 years old when you were 4 years old or she is 2 years younger to you.

Your present age is 100, as your sister is 2 years younger to you, she is 98 years old.

baxthum8 eNotes educator| Certified Educator

Your sister is 2 years younger than you as when you are 4 she is 2(half  your age); therefore when you are 100 your sister is 98 years old.

zanebm11 | Student

When I was 4 years old my sister was half my age, now am 100 how old is my sister

 

When you were 4 years old, your sister would have been 2 years old. This means that you are 2 years older than your sister. The trick here is that they want you to think of yourself as being twice the age of your sister, whereas you are actually only 2 years older. The answer is that when you are 100, your sister will be 2 years younger than you. This would mean that she is 98. 

sammyjo7 | Student

When you were 4 years old, your sister was half your age. Half of 4 is...2. So your sister is 2 years younger than you are. Now that you are 100 your sister is 2 years younger than you, so she is 98 years old. 

atyourservice | Student

` 4-:2 = 2` so you sister is 2 years younger than you

100-2=98   she will be 98