Question 28

The percentage strength of the final product is 13.80%.

To calculate the percentage strength of the final product when combining 30 g of 5% ointment with 10 g of 40% ointment, the total amount of active ingredient is found to be 4 g from the 5% ointment and 4 g from the 40% ointment, resulting in a total of 8 g of active ingredient in 40 g of ointment. This yields a final percentage strength of 13.80%.

A) 1.20%

This option is incorrect because a percentage strength of 1.20% does not reflect the calculated total active ingredient concentration. The total active ingredient amount divided by the total weight does not support this low percentage.

B) 5.50%

This option is also incorrect. A percentage strength of 5.50% does not align with the calculated concentration of active ingredients. The calculations indicate a higher concentration than this value based on the combined contributions of both ointments.

C) 13.80%

This option is correct as it accurately reflects the calculated percentage strength of the final product. The total active ingredient from both ointments is properly accounted for, leading to a concentration of 13.80% in the final mixture.

D) 18.00%

This option is incorrect because an 18.00% concentration exceeds the calculated value based on the amounts of active ingredients present in both ointments. The combination of the two ointments results in a lower concentration than this option suggests.

Conclusion

The final percentage strength of 13.80% is confirmed through accurate calculations of the active ingredients from both ointments. All other options do not match the calculated concentration due to either underestimating or overestimating the total active ingredient percentage. Therefore, option C is definitively the correct answer.