Final answer:
The correct option is 1). John ate 4/10 of a pizza which, when converted into decimal notation, is represented as 0.4.
Step-by-step explanation:
The question is from Mathematics. The amount of pizza that John ate, which is 4/10 of a pizza, can be converted to decimal notation. To do this, we simply divide the numerator by the denominator. This results in 0.4, which is the same as moving the decimal point one place to the right in the numerator (since 4 is equivalent to 4.0). Therefore, the correct decimal notation for the fraction 4/10 is 0.4 hence, correct option is 1).