both not highly correlated, yes you can use.

Yes you can, but be mindful that the reduced range of at least one of the variables will impact your result. Specifically, it will reduce the correlation.

Vitasta Dhawan - Yes, you can also include 'age of the respondents' and 'birth order' while calculating correlation between demographic variables and other variables. Demographic information include: age, race, ethnicity, gender, marital status, income, education, and employment etc. Age is an important variable to consider when analyzing your target audience. Correlation a LINEAR association between two random variables and show us how to determine both the nature and strength of relationship between two variables. Correlation lies between +1 to -1. A zero correlation indicates that there is no relationship between the variables. A correlation of –1 indicates a perfect negative correlation. A correlation of +1 indicates a perfect positive correlation.