Finding average time used in quiz

[cordoprod]

Hi.
I am trying to find the average time used in the quiz.

I am doing this, which always returns 0:

- (float)findAverageTime {
	NSCharacterSet* nonDigits = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
	int value = 0;	
	for(int i=0;i<[userData count];i++) {
		int currentRow = [[[[userData objectAtIndex:i] objectForKey:@"kTimeUsed"] stringByTrimmingCharactersInSet:nonDigits] intValue];
		value += currentRow;
	}
	
	NSLog(@"value : %i", value);
	
	return value/[userData count];
}

I am also trying to use this method, which returns # of passed tests, but i want to display it as percentage. How do i do that?

- (int)passedTests {
	int count = 0;
	
	for(int i=0;i<[userData count];i++) {
		if ([[[userData objectAtIndex:i] objectForKey:@"kPassed"] isEqualToString:@"YES"]) {
			count++;
		}
	}
	
	return count;
}