Round 38.86 to one decimal place

Ineed to know the rule for the sequence. plz !

The brain volumes (cm cubed) of 50 brains vary from a low of 904 cm cubed to a high of 1488 cm cubed. use the range rule of thumb to estimate the standard deviation s and compare the result to the exact standard deviation of 175.5 cm cubed, assuming the estimate is accurate if it is within 15 cm cubed

Given: m∠ adb = m∠cdb ad ≅ dc prove: m∠ bac = m∠bca lol