As we need numbers in positive range, sign bit will stay 0.
about Exponent, we will have to set it to 127 (representation of 0 in Excess 127)
about mantissa, as numbers are of the form (-1)sign * (1,M) * 2(exponent-127) ,1 is implicit.
so we have 2 possibilities now for filling each digit of mantissa(either 0 or 1), making 223 numbers in which '1' is also counted.
Now, as its closed interval, we need to count '2' as well. so, Total 223 + 1 numbers we can represent in the given range.