The answer is 1.5 or 1 1/2
        
             
        
        
        
Well you gotta find out what x means
        
             
        
        
        
There are 45 girls in Jonathan's class.
 
        
             
        
        
        
<span>
The probability of at least three heads can be found by<span><span>∑<span>k=3</span>4</span><span>(<span>4k</span>)</span><span>.5k</span><span>.5<span>4−k</span></span>=<span>516</span></span></span>