To receive Grade ‘A’ in a course, one must obtain an average of 90 marks or more in five examinations (each of 100 marks). If Sunita’s marks in the first four examinations are 87, 92, 94 and 95, find minimum marks that Sunita must obtain in fifth examination to get grade ‘A’ in the course.

Let Sunita's marks in the fith examination be x out of 100 marks. Sunita's marks in the first four examinations are 87, 92, 94 and 95
Average marks obtained by Sunita = 
To receive grade 'A' in a course Sunita has to get an average of 90 marks or more
∴                                          
                                                 
Hence, Sunita must obtain a minimum of 82 marks in the fifth examination to get grade 'A' in the course.