Answer:
605.5
Step-by-step explanation:
When you do a frequency table for this question,the zigma F becomes 2 and the zigma fx becomes 1211.Because you will multiply the marks by the frequency to get the zigma fx so after getting them you add it.Which becomes 403+808=1211.the formula for finding the mean too is zigma fx/zigma f: 1211/2=605.5