This question does not mean much without context. If you’re looking for translations, I would check out one of these sites: https://www.hackingchinese.com/5-websites-to-help-answer-your-questions-about-chinese/

Yes, it’s common; it is rarely mandatory to use both 因为 and 所以. The emphasis/usage is slightly different if you use only 因为, only 所以 or both. Chinese Grammar Wiki has a pretty good description of this with examples. I’m quoting the part that relates directly to your question, but I suggest reading the whole page, including all the examples:

A common way to explain causes in Chinese is with 因为 (yīnwèi). This is equivalent to “because” in English. Usually 因为 (yīnwèi) will begin a new phrase in a sentence.

Structure
In this structure, we first state the result, and then give the reason in the next statement after the 因为 (yīnwèi).

Result, 因为 + Reason

And:

The full pattern 因为……所以…… (yīnwèi… suǒyǐ…) is used to clearly indicate cause and effect. They could be thought of as equating to: “Since ___ happened, so ___ happened.” It sounds weird to use both “since” and “so” in one sentence in English, but it makes everything crystal clear in Chinese.

Structure
因为 + Cause, 所以 + Effect

Yes, you’re perfectly right, of course. I have adjusted this part of the text. Thank you!