#54EasyConditionals· Ranges and Validation

Grade Calculator with Edge Cases

Write `letter_grade(score)` that turns a percentage score into a letter grade and grade points on a 4.0 scale. Return them as one string: the letter, a space, and the points with exactly one decimal place, for example `"B+ 3.3"`. | Score at least | Grade | Points | |---|---|---| | 93 | A | 4.0 | | 90 | A- | 3.7 | | 87 | B+ | 3.3 | | 83 | B | 3.0 | | 80 | B- | 2.7 | | 77 | C+ | 2.3 | | 73 | C | 2.0 | | 70 | C- | 1.7 | | 67 | D+ | 1.3 | | 63 | D | 1.0 | | 60 | D- | 0.7 | | below 60 | F | 0.0 | A boundary belongs to the higher grade: exactly 90 is an A-, while 89.99 is a B+. Return `"Invalid score"` when `score` is not a number (strings and booleans are not numbers here) or when it is below 0 or above 100.

Input format

`score`: usually an int or float, but it may be any JSON value.

Output format

A string such as `"A- 3.7"`, or `"Invalid score"`.

Examples

Input: score = 90

Output: "A- 3.7"

90 meets the A- threshold exactly.

Input: score = 101

Output: "Invalid score"

Scores above 100 are rejected.

Constraints

Valid scores lie in the closed range [0, 100]

Study first

Conditionals: if, elif and else

#python
#conditionals
#validation
#isinstance