Question 1105419
Getting 4 correct is 10C4(1/4)^4(3/4)^6=0.1460.
Scores more than 50% means getting 6 or more right.
Getting 6 right is 210(.25^6)(.75^4)=0.0162; 7 right is 120*.25^7*.75^3=0.003; 8 right 0.0004, 9 right is <0.0001, so the probability is 0.0196

Expected value is X*p(X), so it is $100* probability of 9 or 10+ $50 for probability of 7 or 8.
9 or 10 right is 0.00003 and 10 right is 0.000001, for 0.0000031, the probability for $100=0.000095
for 7 and 8, the probability is 0.0034.  Multiply by $50  to get $0.17. That is the answer given the results for 9 and 10.