3. Compute the variable manufacturing overhead spending and efficiency variances. (Indicate the effect of each variance by selecting "F" for favourable, "U" for unfavourable, and "None" for no effect (i.e., zero variance).) Variable overhead spending variance Variable overhead efficiency variance 4. Compute the fixed overhead budget and volume variances. (Indicate the effect of variance by selecting "F" for favourable, "U" for unfavourable, and "None" for no effect (i.e., zero variance).) Fixed overhead budget variance Fixed overhead volume variance