Price of the scooter: $1890
Duration of the installment plan: 2 years
Annual interest rate: 1.8%

a. Total Interest:
To find the total interest, we'll calculate the simple interest charged on the price of the scooter over the 2-year period.

Simple Interest = Principal * Rate * Time

Principal = $1890
Rate = 1.8% per annum
Time = 2 years

Total Interest = $1890 * 0.018 * 2

b. Amount to Pay Each Month:
To calculate the monthly installment amount, we'll divide the total amount (price + interest) by the number of months in the installment plan.

Total Amount = Price + Total Interest
Number of Months = 2 years * 12 months per year

Amount to Pay Each Month = Total Amount / Number of Months

Now let's perform the calculations:

a. Total Interest:
Total Interest = $1890 * 0.018 * 2 = $68.04

b. Amount to Pay Each Month:
Total Amount = $1890 + $68.04 = $1958.04
Number of Months = 2 years * 12 months per year = 24 months

Amount to Pay Each Month = $1958.04 / 24 ≈ $81.59

Therefore:
a. The total interest to be paid is approximately $68.04.
b. The monthly installment amount is approximately $81.59 (rounded to the nearest cent).